Spinach & Parmesan Stuffed Mushrooms

• 1 lb. medium white mushrooms (about 24), wiped clean
• 5 Tbs. extra-virgin olive oil
• Kosher salt and freshly ground black pepper
• 3 slices white sandwich bread
• 4 scallions (white and green parts), thinly sliced
• 1/4 cup dry sherry
• 6 oz. fresh baby spinach, roughly chopped
• 1/4 cup heavy cream
• 1/3 cup plus 1 Tbs. freshly grated Parmigiano Reggiano
• 1/2 lemon

Set an oven rack 6 inches from the top element and heat the broiler to high. Completely remove the mushroom stems; thinly slice the stems. Set the mushroom caps stem side up on a heavy-duty rimmed baking sheet, drizzle with 1-1/2 Tbs. of the oil, and sprinkle with 1/2 tsp. salt and a few grinds of pepper. Broil until the mushrooms are brown and completely tender, 6 to 7 minutes.

Pulse the bread in a food processor until it forms uniform crumbs. In a large, heavy sauté pan, heat 2 Tbs. of the oil over medium-high heat. Add the breadcrumbs and 1/4 tsp. salt, and cook, stirring constantly, until the breadcrumbs crisp and turn light brown, 4 to 5 minutes. Transfer to a plate and wipe the pan clean. Return the pan to high heat, add the remaining 1-1/2 Tbs. oil and the scallions, and sauté until browned and softened, about 2 minutes. Add the mushroom stems and 1/2 tsp. salt. Cook, stirring, until the stems soften and brown, about 3 minutes. Add the sherry and cook until almost evaporated, 30 to 60 seconds. Add the spinach and stir until it wilts, about 1 minute. Add the cream and 1/3 cup Parmigiano, reduce the heat to medium, and cook until the cream reduces slightly, about 2 minutes. Taste for salt and pepper; let cool.

Discard any liquid that may have accumulated in the mushroom caps. Mound the spinach mixture into the caps; top with the breadcrumbs (press them into the filling) and the remaining 1 Tbs. Parmigiano.

Heat the broiler to high. Broil the caps until the breadcrumbs brown a little more and the mushrooms heat through, 1 to 3 minutes. Squeeze the lemon half over the caps. Serve immediately.

Basic Roasted Mushrooms

You can jazz up this basic recipe by adding Rosemary-Lemon Thyme Oil or Moroccan Spice Rub when you toss the mushrooms with olive oil and salt and pepper before roasting. Or toss the mushrooms with Sesame Sea Salt, Caramelized Shallot Butter, Ginger-Lemon Soy Splash, or Toasted Coriander & Garlic Oil after they come out of the oven.

• 1 lb. mushrooms (cremini or small white), wiped clean, and stems trimmed flush with the cap 
• 1 to 3 Tbs. extra-virgin olive oil
• 1/2 tsp. kosher salt; more to taste
• Freshly ground black pepper
• Fresh lemon juice (optional)

Position a rack in the center of the oven and heat the oven to 475° F. Line a heavy-duty rimmed baking sheet with parchment. In a medium bowl, toss the mushrooms with enough of the olive oil to coat generously, the salt, and a few grinds of pepper. 

Turn the mushrooms out onto the baking sheet and arrange them stem side down. If the mushrooms cover the baking sheet sparsely, arrange them toward the edges of the baking sheet for the best browning. Roast the mushrooms until brown on the bottom, 20 to 25 minutes. Flip and continue to roast until browned on the top, 5 to 10 minutes.

Return the mushrooms to the bowl in which you tossed them with the oil, or put them in a clean serving bowl. If they seem a bit dry, drizzle them with a little oil. Season to taste with salt, pepper, and lemon juice, if using.

Mushroom and Parmesan Soup with Chive Crème Fraîche

Serve this rich and creamy soup with a salad for a weeknight supper or as a starter for a fancier dinner with friends.

• 1-1/2 Tbs. extra-virgin olive oil
• 1 large shallot, minced
• Kosher salt
• 6 oz. white mushrooms, trimmed and thinly sliced (3 cups)
• 3-1/2 oz. shiitake mushrooms, stemmed and thinly sliced (1-1/2 cups)
• 2 tsp. chopped fresh thyme
• Freshly ground black pepper
• 1/3 cup dry sherry
• 2 cups lower-salt chicken broth
• 1 oz. finely grated Parmigiano-Reggiano (1 cup using a rasp grater)
• 1/4 cup crème fraîche, sour cream, or plain Greek yogurt
• 2 Tbs. thinly sliced fresh chives

Heat the oil in a 4-quart saucepan over medium heat. Add the shallot and 1/2 tsp. salt and cook, stirring, until beginning to brown at the edges, 3 to 4 minutes. Add the white and shiitake mushrooms, the thyme, 1/2 tsp. salt, and 1/4 tsp. pepper. Increase the heat to medium high, and cook, stirring, until the mushrooms soften and start to brown, 3 to 5 minutes. Add the sherry and cook, stirring, until reduced by half, about 2 minutes. Add the broth and 1 cup water; bring to a boil. Reduce the heat and simmer for 5 minutes. Stir in the Parmigiano and let cool briefly.

Working in batches, purée the soup in a blender until smooth. Transfer to a 3-quart saucepan and reheat.

In a small bowl, mix the crème fraîche, chives, and 1/8 tsp. black pepper.

Season the soup to taste with salt and pepper and serve topped with a swirl of the crème fraîche.

Crustless Quiche with Ham, Mushrooms & Chives

Take away the fuss of a crust, and a quiche makes a perfect weeknight dinner: quick and delicious. The basic batter is a snap to make, and depending on what you add to it, the variations are endless. You can also bake mini quiches as hors d'oeuvres.

• 1 Tbs. vegetable oil
• 1 Tbs. unsalted butter
• 1/2 lb. white button mushrooms, wiped clean,   stems trimmed, caps quartered (or cut smaller if large)
• Kosher salt
• 6 oz. ham, sliced 1/8 inch thick and cut into 1-1/2x1/2-inch strips
• Freshly ground black pepper
• 1/4 cup cornstarch
• 1-1/4 cups whole milk
• 2 large eggs
• 2 large egg yolks
• 1 cup heavy cream
• 1/2 tsp. kosher salt
• Pinch cayenne
• Butter or oil for the pan
• 2 oz. Gruyère, grated (to yield 1/2 cup)
• 2 Tbs. snipped chives

Position a rack in the top third of the oven and heat the oven to 425°F.

Heat the oil and butter in a 10-inch skillet over medium-high heat. When the butter has melted, add the mushrooms, sprinkle with salt, and cook, stirring occasionally, until softened and browned slightly, about 8 minutes. If the mushrooms release a lot of water, increase the heat to evaporate it. Toss in the ham and cook, stirring frequently, until it has browned a bit, 2 to 3 minutes. Remove from the heat, season with a little salt and pepper, and set aside to cool.

Put the cornstarch in a medium bowl. Whisking steadily, slowly pour in 1/2 cup of the milk, mixing until quite smooth. Whisk in the whole eggs and egg yolks, mixing again until smooth, and then gradually whisk in the rest of the milk, the cream, salt, and cayenne.

Butter or oil a 2-quart, 7x11-inch Pyrex dish or an 8x11-inch ceramic gratin dish. Spread the ham and mushroom mixture over the bottom of the pan. Scatter on the Gruyère and chives.

Whisk the batter in case it has settled and then pour it into the baking dish. Bake until the top is deep golden and the custard is set (insert a pick in the center to check; it should be softly set, neither liquid nor firm), 25 to 30 minutes. Let stand for 30 minutes before serving.

Sherry-Mushroom Gravy

You can serve this zesty gravy over meatloaf or mashed potatoes. Use the Meatloaf Recipe Maker to create a custom meatloaf recipe with your favorite vegetables, herbs, and mix-ins.

• 1 cup lower-salt beef or chicken broth; more as needed
• 2 Tbs. extra-virgin olive oil
• 2 slices center-cut bacon, minced
• 6 oz. cremini (baby bella) or white mushrooms, cleaned and sliced about 1/8 inch thick (2 packed cups)
• 1/2 cup minced yellow onion
• Kosher salt and freshly ground black pepper
• 3 Tbs. dry sherry
• 3 Tbs. all-purpose flour

Combine the broth with 1 cup of hot water. Heat the oil in a 12-inch skillet over medium-high heat. Add the bacon and cook, stirring to break apart the pieces, until just starting to crisp, 1 to 2 minutes. Add the mushrooms, onion, 1/2 tsp. salt, and 1/2 tsp. pepper. Cook, stirring often, until the mushrooms have cooked through and start to brown the bottom of the pan, 5 to 8 minutes.

Add the sherry and stir to release the browned bits from the bottom of the pan, about 1 minute. Sprinkle in the flour and stir constantly until the mixture has browned and is slightly dry and crumbly, about 30 seconds.

Whisk in half of the broth mixture and continue whisking until the liquid is absorbed into the flour, about 30 seconds. Whisk in the remaining broth mixture and bring the gravy to a boil. Reduce the heat and simmer, stirring occasionally, until thickened, 5 to 10 minutes.

Season to taste with salt and pepper and thin with water or broth if necessary. Transfer to a small saucepan, cover, and keep warm. Reheat the gravy if necessary before serving.

Braised Chicken with Caramelized Onions, Mushrooms & Sun-Dried Tomatoes

This quick, saucy dish is great over polenta, pasta, rice, or risotto.

• 1/2 lb. white button mushrooms (or large white mushrooms, quartered)
• Kosher salt and freshly ground black  pepper
• 2 Tbs. extra-virgin olive oil
• 1 Tbs. unsalted butter
• 1-1/2 lb. boneless, skinless chicken breasts, cut into 2-inch chunks
• 1 cup all-purpose flour for dredging
• 3/4 cup homemade or low-salt chicken broth
• 3/4 cup (about half a batch) caramelized onions
• 6 oil-packed sun-dried tomatoes, drained and thinly sliced
• 1 Tbs. balsamic vinegar
• 1/4 tsp. Tabasco sauce
• 1/4 cup chopped fresh flat-leaf parsley

In a medium bowl, toss the mushrooms with 1/2 tsp. salt and a few grinds of pepper. Heat the oil and butter in a large skillet over medium-high heat until the butter melts and most of its foam cooks off, about 1 min. Meanwhile, season the chicken with 3/4 tsp. salt and a few generous grinds of pepper. Spread the flour on a large plate and lightly dredge the chicken. Sauté the chicken pieces, flipping after 2  min., until they’re lightly brown on both sides, about 4 min. total (it’s all right if the sides of the chicken are still raw). Add the mushrooms and cook, stirring, until they start to soften and brown in places, about 3 min. Add the chicken broth, caramelized onions, and sun-dried tomatoes. Bring to a boil and then reduce to a gentle simmer. Cover and cook until the chicken is firm to the touch and cooked through (check by slicing into one of the thicker pieces) and the mushrooms are tender, about 6 min. Stir in the vinegar, the Tabasco, and half of the parsley. Taste for salt and pepper and serve sprinkled with the remaining parsley.

Classic Beef Stroganoff

This classic stroganoff recipe features thin slices of sautéed beef with mushrooms and onions in a sour cream sauce, all served over buttery egg noodles. It's a rich yet homey meal that comes together quickly enough to make even on a weeknight.

• Kosher salt
• 1-1/2 lb. beef top round or shell steak, sliced 1/4 inch thick, slices cut crosswise into 1-inch pieces
• Freshly ground black pepper
• 2 Tbs. canola oil
• 3 Tbs. unsalted butter
• 10 oz. white button mushrooms, cut into 1/4-inch-thick slices (4 cups)
• 1 cup finely chopped yellow onion (about half a medium onion)
• 1 Tbs. all-purpose flour
• 1 cup lower-salt beef broth
• 1 cup full-fat sour cream, at room temperature
• 1 12-oz. package wide egg noodles
• 1 Tbs. thinly sliced fresh chives

Tip:

Use reduced-fat sour cream at your own risk; it will likely curdle.

Bring a large pot of well-salted water to a boil over high heat.

Season the beef with 1 tsp. salt and 3/4 tsp. pepper. Heat 2 tsp. of the oil in a 12-inch skillet over medium-high heat until very hot. Add half of the beef and cook, stirring often, until the meat is just browned, about 1 minute; do not overcook. Transfer to a plate and repeat with 2 tsp. of the oil and the remaining beef.

Remove the skillet from the heat. Add 1 Tbs. of the butter and the remaining 2 tsp. oil to the skillet and stir until the butter melts. Put the skillet over medium heat and add the mushrooms. Cook, stirring occasionally, until the mushrooms release their liquid, about 5 minutes. Add the onions and cook, stirring occasionally, until the liquid has evaporated and the onions are beginning to soften, about 3 minutes more.

Sprinkle the mushroom mixture with the flour and stir for 15 seconds. Stir in the broth and bring to a simmer, scraping up any browned bits in the skillet with a wooden spoon. Add the sour cream and whisk until the sauce is smooth. Add the beef and any juices from the plate to the skillet. Cook, stirring often, until the sauce is barely simmering. Season to taste with salt and pepper.

Meanwhile, cook the noodles according to the package directions in the boiling water until barely tender. Drain and return to the pot. Off the heat, add the remaining 2 Tbs. butter and stir to melt. Season to taste with salt and pepper.

Serve the beef Stroganoff over the noodles, sprinkled with the chives.

Parmigiano-Stuffed Mushrooms

Finely ground Parmigiano-Reggiano adds great texture (and flavor) to the stuffing in these savory, three-bite appetizers.

• 2 oz. (4 Tbs.) unsalted butter
• 24 large white button mushrooms (about 2-1/2 inches wide; 2-1/2 lb. total), stemmed; stems finely chopped and caps wiped clean
• Kosher salt
• 3 oz. Parmigiano-Reggiano, finely ground in a food processor (3/4 cup)
• 3/4 cup plain panko
• 1/3 cup mayonnaise
• 1/4 cup finely chopped fresh flat-leaf parsley
• Freshly ground black pepper
• 1-1/2 Tbs. extra-virgin olive oil

Position a rack in the center of the oven and heat the oven to 400°F.

Melt the butter in a 10-inch nonstick skillet over medium heat. Set aside 2 Tbs. of the melted butter in a small bowl. Add the mushroom stems and 1/4 tsp. salt to the skillet and cook, stirring often with a wooden spatula, until tender, about 5 minutes. Let cool to room temperature.

Meanwhile, add 2 Tbs. of the Parmigiano and the panko to the reserved melted butter and mix thoroughly; set aside.

In a medium bowl, stir together the remaining Parmigiano, the mayonnaise, parsley, and 1/4 tsp. black pepper. Add the mushroom stems and mix until well combined.

In a large bowl, toss the mushroom caps with the oil. Fill each mushroom cap with a rounded teaspoon of the filling and top each with about 1 tsp. of the panko mixture. Place on a large rimmed baking sheet with space in between. Bake until tender and the topping is golden-brown, about 25 minutes. Cool briefly before serving.

Crustless Quiche with Ham, Mushrooms & Chives

Take away the fuss of a crust, and a quiche makes a perfect weeknight dinner: quick and delicious. The basic batter is a snap to make, and depending on what you add to it, the variations are endless. You can also bake mini quiches as hors d'oeuvres.

• 1 Tbs. vegetable oil
• 1 Tbs. unsalted butter
• 1/2 lb. white button mushrooms, wiped clean,   stems trimmed, caps quartered (or cut smaller if large)
• Kosher salt
• 6 oz. ham, sliced 1/8 inch thick and cut into 1-1/2x1/2-inch strips
• Freshly ground black pepper
• 1/4 cup cornstarch
• 1-1/4 cups whole milk
• 2 large eggs
• 2 large egg yolks
• 1 cup heavy cream
• 1/2 tsp. kosher salt
• Pinch cayenne
• Butter or oil for the pan
• 2 oz. Gruyère, grated (to yield 1/2 cup)
• 2 Tbs. snipped chives

Position a rack in the top third of the oven and heat the oven to 425°F.

Heat the oil and butter in a 10-inch skillet over medium-high heat. When the butter has melted, add the mushrooms, sprinkle with salt, and cook, stirring occasionally, until softened and browned slightly, about 8 minutes. If the mushrooms release a lot of water, increase the heat to evaporate it. Toss in the ham and cook, stirring frequently, until it has browned a bit, 2 to 3 minutes. Remove from the heat, season with a little salt and pepper, and set aside to cool.

Put the cornstarch in a medium bowl. Whisking steadily, slowly pour in 1/2 cup of the milk, mixing until quite smooth. Whisk in the whole eggs and egg yolks, mixing again until smooth, and then gradually whisk in the rest of the milk, the cream, salt, and cayenne.

Butter or oil a 2-quart, 7x11-inch Pyrex dish or an 8x11-inch ceramic gratin dish. Spread the ham and mushroom mixture over the bottom of the pan. Scatter on the Gruyère and chives.

Whisk the batter in case it has settled and then pour it into the baking dish. Bake until the top is deep golden and the custard is set (insert a pick in the center to check; it should be softly set, neither liquid nor firm), 25 to 30 minutes. Let stand for 30 minutes before serving.

Duxelles

Duxelles is a mixture of finely chopped mushrooms, shallots, and sometimes herbs that is cooked slowly in butter until it becomes thick. The Duxelles here is used as a filling for Potato Pancakes (Latkes).

• 6 oz. white button mushrooms, cleaned and thinly sliced (about 2 cups)
• 10 oz. shiitake mushrooms, stems removed and discarded, caps cleaned and thinly sliced (about 3 cups)
• 2 large shallots, peeled and thinly sliced
• 4 Tbs. unsalted butter
• 3/4 tsp. kosher salt
• 1/8 tsp. freshly ground black pepper

Tip:

Mushrooms are 90% water; the long, slow cooking of duxelles will evaporate the water and concentrate the mushroom flavor. Save any leftover duxelles in the freezer—it’s great in omelets, stuffed under the skin of a roasted chicken, or stuffed in baby squash or cherry tomatoes.

Put the mushrooms and shallots in a food processor fitted with the chopping blade. Pulse until finely chopped. The mushrooms and shallots should be in about 1/8-inch pieces—don’t overprocess.

Melt the butter in a 10-inch skillet over medium heat. Add the mushroom mixture, salt, and pepper and cook, stirring. When the mushrooms begin to release their moisture, turn the heat to low and cook, stirring occasionally, until the liquid has evaporated and the duxelles look dry, 20 to 25 minutes. Let cool.

Mushroom & Roasted Garlic Succotash

This wintertime version of succotash features mushrooms instead of corn. You can use all button mushrooms or a mix, including shiitake, cremini, and your favorite wild mushrooms.

• 1 head garlic
• 1 Tbs. olive oil
• 2 slices bacon, chopped
• 1 1/2 cups chopped onion
• 1 Tbs. finely chopped garlic
• 6 cups sliced fresh mushrooms (about 1 lb.)
• 1 cup homemade or low-salt chicken broth
• 1/2 cup finely chopped red bell pepper
• 3 cups (about 13 oz.) frozen lima beans, thawed
• 2 tsp. chopped fresh rosemary
• Kosher salt and freshly ground black pepper

Heat the oven to 400°F. Cut off the top third of the head of garlic to expose the cloves. Coat the cut side with the olive oil. Wrap the garlic loosely in foil, put it on a baking sheet, and roast until very soft, about 1 hour. When cool enough to handle, squeeze out the soft garlic; set aside.

In a large skillet over medium-high heat, cook the bacon until crisp. Add the onion and chopped garlic and sauté until softened, about 2 minutes. Add the mushrooms and sauté until softened and lightly browned. Add the broth, roasted garlic, red pepper, and lima beans; cook until the beans are tender and the liquid is reduced, about 10 minutes. Add the rosemary and season with salt and pepper to taste.

Mushroom and Parmesan Soup with Chive Crème Fraîche

Serve this rich and creamy soup with a salad for a weeknight supper or as a starter for a fancier dinner with friends.

• 1-1/2 Tbs. extra-virgin olive oil
• 1 large shallot, minced
• Kosher salt
• 6 oz. white mushrooms, trimmed and thinly sliced (3 cups)
• 3-1/2 oz. shiitake mushrooms, stemmed and thinly sliced (1-1/2 cups)
• 2 tsp. chopped fresh thyme
• Freshly ground black pepper
• 1/3 cup dry sherry
• 2 cups lower-salt chicken broth
• 1 oz. finely grated Parmigiano-Reggiano (1 cup using a rasp grater)
• 1/4 cup crème fraîche, sour cream, or plain Greek yogurt
• 2 Tbs. thinly sliced fresh chives

Heat the oil in a 4-quart saucepan over medium heat. Add the shallot and 1/2 tsp. salt and cook, stirring, until beginning to brown at the edges, 3 to 4 minutes. Add the white and shiitake mushrooms, the thyme, 1/2 tsp. salt, and 1/4 tsp. pepper. Increase the heat to medium high, and cook, stirring, until the mushrooms soften and start to brown, 3 to 5 minutes. Add the sherry and cook, stirring, until reduced by half, about 2 minutes. Add the broth and 1 cup water; bring to a boil. Reduce the heat and simmer for 5 minutes. Stir in the Parmigiano and let cool briefly.

Working in batches, purée the soup in a blender until smooth. Transfer to a 3-quart saucepan and reheat.

In a small bowl, mix the crème fraîche, chives, and 1/8 tsp. black pepper.

Season the soup to taste with salt and pepper and serve topped with a swirl of the crème fraîche.

Classic Beef Stroganoff

This classic stroganoff recipe features thin slices of sautéed beef with mushrooms and onions in a sour cream sauce, all served over buttery egg noodles. It's a rich yet homey meal that comes together quickly enough to make even on a weeknight.

• Kosher salt
• 1-1/2 lb. beef top round or shell steak, sliced 1/4 inch thick, slices cut crosswise into 1-inch pieces
• Freshly ground black pepper
• 2 Tbs. canola oil
• 3 Tbs. unsalted butter
• 10 oz. white button mushrooms, cut into 1/4-inch-thick slices (4 cups)
• 1 cup finely chopped yellow onion (about half a medium onion)
• 1 Tbs. all-purpose flour
• 1 cup lower-salt beef broth
• 1 cup full-fat sour cream, at room temperature
• 1 12-oz. package wide egg noodles
• 1 Tbs. thinly sliced fresh chives

Tip:

Use reduced-fat sour cream at your own risk; it will likely curdle.

Bring a large pot of well-salted water to a boil over high heat.

Season the beef with 1 tsp. salt and 3/4 tsp. pepper. Heat 2 tsp. of the oil in a 12-inch skillet over medium-high heat until very hot. Add half of the beef and cook, stirring often, until the meat is just browned, about 1 minute; do not overcook. Transfer to a plate and repeat with 2 tsp. of the oil and the remaining beef.

Remove the skillet from the heat. Add 1 Tbs. of the butter and the remaining 2 tsp. oil to the skillet and stir until the butter melts. Put the skillet over medium heat and add the mushrooms. Cook, stirring occasionally, until the mushrooms release their liquid, about 5 minutes. Add the onions and cook, stirring occasionally, until the liquid has evaporated and the onions are beginning to soften, about 3 minutes more.

Sprinkle the mushroom mixture with the flour and stir for 15 seconds. Stir in the broth and bring to a simmer, scraping up any browned bits in the skillet with a wooden spoon. Add the sour cream and whisk until the sauce is smooth. Add the beef and any juices from the plate to the skillet. Cook, stirring often, until the sauce is barely simmering. Season to taste with salt and pepper.

Meanwhile, cook the noodles according to the package directions in the boiling water until barely tender. Drain and return to the pot. Off the heat, add the remaining 2 Tbs. butter and stir to melt. Season to taste with salt and pepper.

Serve the beef Stroganoff over the noodles, sprinkled with the chives.

Roasted Potato and Mushroom Salad with Mascarpone

Roasting the potatoes and mushrooms deepens the flavor of this warm salad, and the mascarpone dressing adds richness and tang.

• 6 Tbs. extra-virgin olive oil
• 2 lb. Yukon gold potatoes (about 6 medium), halved and cut into 3/4-inch wedges
• Kosher salt and freshly ground black pepper
• 3/4 lb. small to medium cremini or white mushrooms, quartered
• 1/2 cup mascarpone
• 1/4 cup fresh orange juice
• 1-1/2 tsp. red wine vinegar
• 1/3 cup thinly sliced scallions, white and green parts (about 4 small)

Position a rack in the center of the oven and heat the oven to 450°F. Coat a large rimmed baking sheet with 1 Tbs. of the oil.

In a large bowl, toss the potatoes, 2 Tbs. of the oil, 1 tsp. salt, and 1/2 tsp. pepper. Arrange in a single layer on the prepared baking sheet. Roast until barely tender, about 20 minutes, gently tossing with a spatula halfway through.

Meanwhile, toss the mushrooms, 1 Tbs. of the oil, 1/2 tsp. salt, and 1/4 tsp. pepper in the bowl.

Gently toss the potatoes again, scatter the mushrooms evenly over the potatoes, and continue to roast until both the potatoes and mushrooms are tender and golden brown in spots, 10 to 15 minutes more.

Meanwhile, in a medium bowl, whisk the mascarpone, orange juice, vinegar, 1 tsp. salt, and 1/8 tsp. pepper. Drizzle in the remaining 2 Tbs. oil while whisking constantly; set aside.

Return the potatoes and mushrooms to the large bowl and add the mascarpone dressing. Toss gently to coat, season to taste with salt and pepper, and transfer to a large serving bowl. Garnish with the scallions and serve.