Raspberry-Peach Trifle Cake

To prepare cake layers: Butter the bottom and sides of two 9-inch round cake pans; line the bottoms with parchment paper. Preheat oven to 350 degrees F.

Combine milk and 4 tablespoons butter in a small saucepan. Heat over low heat until the butter is just melted. Set the pan aside.

Stir flour and baking powder together, then sift onto a piece of parchment paper.

Whisk eggs in a mixing bowl by hand to combine, then whisk in salt. Whisk in sugar in a stream, then whisk in vanilla. Then, using a hand-held electric mixer or a stand mixer with the whisk attachment, whip the mixture on medium-high speed until lighter in color and very light and fluffy in texture, about 3 minutes in a stand mixer or 5 minutes with a hand mixer.

Gently whisk in the warm milk mixture by hand. Add the flour mixture in 4 additions, lifting the parchment paper to help you sprinkle it in. Use the whisk as you would a rubber spatula to fold the flour into the liquid, gently whisking to incorporate each time. Divide the batter between the prepared pans and smooth the tops.

Bake in the center of the oven until golden and firm when touched in the center, about 20 minutes. Let cool in the pans on a wire racks for 10 minutes.

Run a sharp paring knife around the layers to loosen, then invert the pans onto the racks. Immediately turn the layers over so they cool with the paper on the bottom. Let cool completely.

To prepare peaches: Bring water, 1/2 cup sugar and vanilla beans to a boil in a large pot. Add peaches and return to a boil, then remove from heat. Place a plate on top of the peaches to submerge them in the syrup; let stand while you prepare the custard.

To prepare custard: Combine 1 1/2 cups milk and 1/3 cup sugar in a medium nonreactive saucepan. Whisk cornstarch and the remaining 1/2 cup milk in a medium bowl until smooth, then whisk in egg yolks. Place the saucepan over medium-low heat and heat until steaming. Whisk a third of the steaming milk into the yolk mixture. Bring the remaining milk to a boil over medium heat. As soon as it boils, start whisking and add the yolk mixture all at once while constantly whisking. Continue cooking, whisking constantly, until the custard thickens and starts to bubble, about 2 minutes. Remove from heat and whisk in 2 teaspoons vanilla extract. Scrape the custard into a nonreactive bowl (see Tip, page 73) and press a piece of plastic wrap directly on the surface. Refrigerate until cold, at least 2 hours.

When the peaches have cooled, remove from the syrup with a slotted spoon and peel. Return the peaches to the syrup and refrigerate while the custard chills.

When you're ready to assemble the cake, use the slotted spoon to transfer the peaches to a paper-towel-covered baking sheet to drain. Bring the peach syrup to a boil over high heat; boil until reduced by half, 6 to 10 minutes. Carefully pour the syrup into a heatproof bowl to cool. Slice the peaches into 1/4-inch-thick slices.

To prepare topping: Whip cream in a medium bowl with 1 tablespoon sugar and vanilla extract (or paste) until soft peaks form.

To assemble cake: Using a large serrated knife, cut each cake layer in half horizontally so you have 4 very thin layers of cake (see Tips). Place one layer cut-side-up on a serving platter. Brush with 1/4 cup of the peach syrup. Spread on one-third of the custard and top with one-fourth of the sliced peaches and 1/2 cup raspberries. (see Tips). Repeat with two more cake layers, with the same amounts of syrup, custard and peaches and raspberries. Place the final layer, cut-side up, on top and brush with 1/4 cup of the syrup. Top with the whipped cream and the remaining peaches and 1/2 cup raspberries.