Lemon-Buttermilk Pudding Cakes

These cakes have a thin layer of pudding on the bottom and a cheesecake-like layer on the top.

• 1-1/2 oz. (3 Tbs.) unsalted butter, melted and cooled slightly, plus about 2 tsp. more, softened, for the ramekins
• 3/4 cup granulated sugar
• 3 large egg yolks, at room temperature
• 1 cup buttermilk, at room temperature
• 1/4 cup whole milk, at room temperature
• 1-1/8 oz. (1/4 cup) all-purpose flour
• 1/4 tsp. table salt
• 1/3 cup fresh lemon juice, at room temperature
• 4 large egg whites, at room temperature
• 1 Tbs. finely grated lemon zest
• 1/2 cup lightly sweetened whipped cream, for serving (optional)
• 1 cup fresh raspberries, blackberries, blueberries, or sliced strawberries, for serving (optional)

Position a rack in the center of the oven and heat the oven to 350°F. Butter eight 6-oz. ramekins and arrange them in a roasting pan or in two 8x8-inch Pyrex baking dishes. Fill a kettle with about 6 cups of water. Bring to a boil and set aside.

In a large bowl, whisk the melted butter with 1/2 cup of the sugar and the egg yolks until smooth and light, about 1 minute. Whisk in the buttermilk, milk, flour, and salt just until smoothly blended. Whisk in the lemon juice.

In a large bowl, beat the egg whites with an electric mixer (a hand-held or stand mixer fitted with a whisk attachment) on medium speed until frothy, 30 to 60 seconds. Increase the speed to high and beat just until the whites hold soft peaks—the peak should flop over immediately when the beater is lifted—30 to 60 seconds. Reduce the mixer speed to medium and very slowly sprinkle in the remaining 1/4 cup sugar. If necessary, stop the mixer and scrape down the sides of the bowl. Beat on high speed until the whites hold medium-firm peaks—the peak should hold its shape pretty well when the beater is lifted, but the tip will curl over on itself—30 to 60 seconds.

Spoon one-third of the whites onto the egg yolk mixture, sprinkle with the lemon zest, and gently whisk to blend. Using the whisk, gently fold and stir the remaining whites into the batter. The batter will be light and foamy but thin.

Spoon the mixture evenly among the ramekins—you can fill them to the top. Put the roasting pan with the ramekins in the oven and pour enough hot water from the kettle into the pan to reach about halfway up the sides of the ramekins. Bake until the tops of the cakes are light golden and puffed, 25 to 30 minutes. They should spring back slightly when touched. Take the cakes out of the water bath and let cool on a rack to room temperature. Then refrigerate for at least 2 hours and up to 24 hours before serving. Top the cakes with a small dollop of whipped cream and garnish with a few fresh berries, if using.