Martha Stewart's Lemon Mousse Cake

Preparation

Make the cake: Preheat oven to 350 F. Butter two 9-inch round cake pans. Line with parchment; butter parchment. Dust with flour, tapping out any excess. In a small bowl, whisk together milk, eggs and vanilla seeds.

In a large bowl, with an electric mixer, beat together flour, sugar, baking powder, and salt on low speed until well combined. Continue beating while gradually adding butter until mixture is crumbly, about 3 minutes.

Slowly add half the milk mixture; increase speed to medium and beat until fluffy, about 2 minutes. Slowly add remaining half of milk mixture, scraping down sides of bowl as needed. Add lemon zest and beat until incorporated, about 1 minute more.

Divide batter evenly between prepared pans, smoothing tops with a small offset spatula. Bake until golden brown and a cake tester comes out clean, 35 to 40 minutes. Transfer pans to a wire rack; let cool completely. Turn cakes out of pans and remove parchment.

Make the filling: In a small bowl, sprinkle gelatin over cold water. Let stand until softened, about 5 minutes. In a small, heavy saucepan, whisk together yolks, sugar and lemon zest and juice. Cook, whisking constantly, over medium-low heat, until mixture is thick enough to coat the back of a spoon, 8 to 10 minutes. Remove pan from heat; add gelatin mixture, stirring constantly, until gelatin is dissolved, and mixture is slightly cool. Add butter, a few pieces at a time, stirring well after each addition, until smooth. Press filling through a fine sieve into a bowl. Cover with plastic wrap, pressing it directly onto surface to prevent skin from forming, and refrigerate until set, at least 2 hours and up to overnight. Stir filling; gently fold in whipped cream. Refrigerate 1 hour. Stir before using.

With a serrated knife, trim tops of cakes to level; split each cake in half horizontally to form a total of 4 layers. Place a cake layer, bottom-side down, on a cake stand. Spread 1 heaping cup of filling to the edges with an offset spatula. Repeat process with 2 more cake layers. Top with remaining cake layer, bottom-side up. Refrigerate while you make meringue.

Make the Swiss meringue: In a heatproof bowl set over (not in) a pot of simmering water, combine sugar, egg whites and salt. Whisk until sugar is dissolved and mixture is warm to the touch and feels completely smooth when rubbed between fingertips, 2 to 3 minutes. Remove bowl from heat. With an electric mixer, whisk on low speed until foamy. Increase speed to medium-high and whisk until stiff, glossy peaks form and mixture cools completely, about 10 minutes. Add vanilla, cornstarch and vinegar; whisk until incorporated, about 1 minute more.

Evenly spread top and sides of cake with a 1/2-inch thickness of meringue, smoothing with an offset spatula. Transfer remaining meringue to a pastry bag fitted with a 3/4-inch round tip. Position tip parallel to top of cake, about 1 inch from edge. Pipe meringue, using an even amount of pressure and dragging tip along surface and down side of cake, on the diagonal, and working from right to left. Continue piping, rotating cake, to cover completely. Use a kitchen torch to toast meringue, moving flame back and forth until evenly browned. Top with raspberries just before serving.

Reprinted from Martha Stewart's Cake Perfection. Copyright © 2020 by Martha Stewart Living Omnimedia, Inc. Published by Clarkson Potter, an imprint of Penguin Random House, LLC.