MARTHA'S BIRTHDAY CAKE

Steps:

• Preheat the oven to 350°F. Generously butter the inside of a 10-inch stainless steel bowl (4 1/2 to 6 inches deep). Dust with flour, and tap out excess; set aside. Into a medium mixing bowl, sift together flour, baking powder, and 1/4 teaspoon salt.
• In the bowl of an electric mixer fitted with the paddle attachment, beat butter, 2 cups sugar, and vanilla seeds on medium speed until light and fluffy, about 3 minutes, scraping down the sides of the bowl as needed. With the mixer on low speed, add the flour mixture in four parts, alternating with the milk and beginning and ending with the flour; beat until just combined. Transfer mixture to a large, wide bowl; set aside.
• With a clean bowl and whisk attachment, beat the egg whites and the pinch of salt on high speed until soft peaks form. Add the remaining tablespoon sugar, and continue to beat until medium-stiff peaks form, about 2 minutes. Whisk a third of the egg-white mixture into the butter-flour mixture to lighten, then use a rubber spatula to gently fold in remaining whites until just combined.
• Pour the batter into the prepared bowl, and smooth the top with an offset spatula. Bake, rotating bowl halfway through, until the cake is golden brown and a cake tester inserted in the center comes out clean, about 1 hour 40 minutes. (If the cake begins to get too dark, cover loosely with aluminum foil.) Transfer bowl to a wire rack to cool for 30 minutes. Invert cake onto the rack and let cool completely.
• Line a bowl slightly smaller than the cake with plastic wrap, leaving some overhang. Fit cake into bowl. Using a serrated knife, trim the bottom of the cake to make level. Invert cake onto a clean work surface or cake turntable. Using the serrated knife, cut cake horizontally into four layers of approximately the same height.
• Place the bottom (largest) layer on a cardboard round or serving plate. Brush the top liberally with Amaretto Simple Syrup. Using an offset spatula, evenly spread about 1 cup Almond Buttercream over the top, about 1/4 inch thick. Top with the next-largest layer, and brush with syrup. Spread apricot jam in an even layer over the top. Place the next-largest layer, and brush with syrup. Spread about 1/2 cup buttercream over the top. Place remaining (smallest) layer on top. Brush the surface of the entire cake with syrup. Spread about 1/2 cup buttercream over the entire cake in a thin layer. Cake can be made up to this point up to 1 day in advance; refrigerate, covered, until ready to proceed.
• Fill a pastry bag fitted with a large star tip (such as an Ateco #5) with Almond Swiss Meringue. Pipe stars to cover the entire surface of the cake, pulling up as you pipe to form points. Using a small kitchen torch, lightly brown the meringue all over. Let cake stand at room temperature until ready to serve, up to 6 hours.
• In the heatproof bowl of an electric mixer, combine egg whites, sugar, salt, and almond extract. Set the bowl over a pan of gently simmering water. Whisk constantly until the sugar has dissolved and whites are hot to the touch, 3 to 5 minutes. Using a rubber spatula, scrape down the sides of the bowl.
• Attach the bowl to the electric mixer fitted with the whisk attachment; mix on medium-high speed, about 2 minutes. Raise speed to high and beat until stiff, glossy peaks form, about 6 minutes. Use immediately.
• The cake is baked in a stainless steel bowl, which gives the cake a dome shape when inverted.
• After splitting the dome into four layers, almond-flavored buttercream and apricot jam are used to flavor alternating layers.
• The filled cake is given a crumb coat of buttercream before its final layer of piped meringue.