German Chocolate Cake With Coconut-Pecan Filling

1. FOR THE FILLING: Whisk egg yolks in medium saucepan, then gradually whisk in evaporated milk. Add granulated sugar, brown sugar, 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 bowl, whisk in vanilla, then stir in coconut. Cool until just warm, cover with plastic wrap, and refrigerate until cool or cold, at least 2 hours or up to 3 days. (Do not stir in pecans until just before cake assembly.)
2. FOR THE CAKE: Adjust oven rack to lower-middle position and heat oven to 350 degrees. Grease two 9-inch round cake pans, line with parchment paper, grease parchment, and flour pans. Combine chocolate and cocoa in small heatproof bowl, pour boiling water over mixture, and let sit, covered, for 5 minutes. Whisk mixture gently until smooth, then let cool to room temperature. Whisk flour and baking soda together in medium bowl and set aside.
3. Using stand mixer fitted with paddle, beat butter, granulated sugar, brown sugar, and salt on medium-high until light and fluffy, about 3 minutes. Add eggs, 1 at a time, and beat until combined. Beat in vanilla, increase speed to medium-high and beat until light and fluffy, about 45 seconds. Reduce speed to low, add chocolate, then increase speed to medium and beat until combined, about 30 seconds, scraping down bowl once (batter may appear curdled). Reduce speed to low, add flour mixture in 3 additions, alternating with 2 additions of sour cream, scraping down bowl as needed. Give batter final stir by hand (batter will be thick).
4. Divide batter evenly between prepared pans and smooth tops with rubber spatula. Bake cake until toothpick inserted in centers comes out clean, about 30 minutes, switching position of pans twice through baking, so each cake spends same amount of time in each position. Let cakes cool in pans on wire rack for 10 minutes. Remove cakes from pans, discard parchment, and let cool completely, about 2 hours, before filling. (Cooled cakes can be wrapped tightly in plastic wrap and kept at room temperature for up to 1 day. Wrapped tightly in plastic, then aluminum foil, cakes can be frozen for up to 1 month. Defrost cakes at room temperature before unwrapping and frosting.)
5. TO ASSEMBLE THE CAKE: Place cooled cake layers on top of each other and make 1⁄8-inch-deep vertical cut into side of each cake layer. With long serrated knife, use sawing motion to cut cakes in half horizontally so that each cake forms two layers.
6. Line edges of cake platter with 4 strips of parchment paper to keep platter clean. Place 1 cake layer on prepared platter. Stir toasted pecans into chilled filling. Spread 1 cup filling evenly across top of cake layer, spreading filling to very edge. Carefully place next cake layer on top of filling, aligning cuts so that layers are even. Repeat using remaining filling and cake layers. Carefully pull out pieces of parchment from beneath cake before serving. (Assembled cake can be refrigerated for up to 1 day. Bring to room temperature before serving.)

GERMAN CHOCOLATE CAKE WITH BANANA, MACADAMIA, AND COCONUT FILLING
If you cannot find roasted unsalted macadamia nuts, substitute salted ones, but first remove excess salt by spreading them on a clean kitchen towel and giving them a good rub.
Reduce vanilla in filling to 1 teaspoon and add 2 teaspoons dark rum with vanilla in step 1. Substitute unsalted macadamia nuts for pecans. Just before assembling cake, peel and cut 4 bananas into 3⁄8-inch-thick slices. Arrange one quarter of banana slices on first cake layer, then spread filling evenly over; repeat with remaining cake layers, bananas, and filling.

GERMAN CHOCOLATE CAKE WITH COFFEE, CASHEW, AND COCONUT FILLING
Add 2 teaspoons ground coffee to filling mixture with sugars in step 1. Substitute roasted unsalted cashews for pecans.

GERMAN CHOCOLATE SHEET CAKE

SERVES 15
The towering layers of chocolate cake separated by coconut-pecan filling look impressive in our German Chocolate Cake, but splitting the cake layers and assembling the cake is a fair amount of work, so we developed this simplified sheet cake variation, which slathers the entire cake with a thick layer of the coconut-pecan filling. In addition to being easier to assemble, the cake is also a cinch to serve to crowds. When you frost the cake, the frosting should be cool or cold (or room temperature, at the very warmest). To be time-efficient, first make the frosting, then use the refrigeration time to prepare, bake, and cool the cake. The toasted pecans are stirred into the frosting just before the cake is frosted to keep them from becoming soft and soggy.
Grease 13 by 9-inch baking pan, line with parchment paper, grease parchment, and flour pan. Follow recipe as directed through step 3, preparing filling to use as frosting. In step 4, pour batter into prepared pan, smooth top with rubber spatula, and gently tap pan on counter to release air bubbles. Bake cake until toothpick inserted in center comes out clean, 30 to 35 minutes. Let cake cool in pan on wire rack for 10 minutes. Remove cake from pan, discard parchment, and let cool completely, about 2 hours, before frosting. Frost top of cake and serve. (Refrigerate cake if not serving immediately; if refrigerated longer than 2 hours, let cake sit at room temperature 15 to 20 minutes before serving. Cooled, unfrosted cake can be stored at room temperature for up to 1 day. Frosted cake can be refrigerated for up to 3 days.)