German Chocolate Cake

To make the filling, in a medium saucepan, whisk yolks; gradually whisk in evaporated milk. Add sugars, butter, and salt and cook over medium-high heat, whisking constantly, until mixture is boiling, frothy and slightly thickened, about 6 minutes. Transfer mixture to a heat proof bowl, whisk in vanilla, then stir in coconut. Cool until just warm, cover with plastic wrap, and refrigerate until cold, at least 2 hours or up to 3 days.

To make the cake, heat oven to 350 degrees. Spread pecans on a baking sheet and toast until fragrant and browned, about 8 minutes; set aside to cool.

In a small bowl, combine chocolate and cocoa; pour boiling water over the chocolate and let stand to melt, about 2 minutes. Whisk until smooth; set aside until cooled to room temperature.

Spray two 9-inch-round by 2-inch-high straight-sided cake pans with nonstick cooking spray; line bottoms with parchment paper rounds. Spray paper rounds, dust pans with flour, and knock out excess.

In a medium bowl, sift together the flour and baking soda.

In bowl of a stand mixer fitted with the paddle attachment, beat butter, sugars, and salt at medium-low speed until sugar is combined, about 30 seconds. Increase speed to medium-high and beat until mixture is light and fluffy, about 4 minutes, scraping down bowl with rubber spatula halfway through. With mixer running at medium speed, add eggs one at a time, beating well after each addition and scraping down bowl halfway through. Beat in vanilla; increase speed to medium-high and beat until light and fluffy, about 45 seconds. With mixer running at low speed, add chocolate, then increase speed to medium and beat until combined, about 30 seconds, scraping down bowl once. With mixer running at low speed, add dry ingredients in 3 additions, alternating with sour cream (in 2 additions), beginning and ending with dry ingredients, and beating in each addition until just combined. After final flour addition, beat on low until just combined, then stir batter by hand with rubber spatula, scraping bottom and sides of bowl (batter will be thick). Divide batter evenly between prepared cake pans; spread batter to edges of pans with rubber spatula and smooth surfaces.

Bake cakes until toothpick inserted into center of cakes comes out clean, about 28-30 minutes. Cool in pans 10 minutes, then invert cakes onto greased wire rack; peel off and discard paper rounds. Cool cakes to room temperature before filling.

To assemble the cake, stir toasted pecans into chilled filling. With a serrated knife held so that blade is parallel with work surface, use a sawing motion to cut each cake into two even layers. Starting with first cake, carefully lift off top layer and set aside. Place the bottom layer on a serving plate and using an icing spatula, distribute about 1 cup filling evenly on cake, spreading filling to very edge of cake and leveling surface. Carefully place upper cake layer on top of filling; repeat using remaining filling and cake layers. Serve or refrigerate cake, covered loosely with foil, up to 4 hours (if refrigerated longer than 2 hours, let cake stand at room temperature 15 to 20 minutes before serving).