German Chocolate Cake

For cake: In a small saucepan, combine the water and cocoa powder. Bring to a boil over medium, stirring constantly. Remove from heat; let cool.

Preheat oven to 350°. Lightly grease the bottoms of three 9-inch round cake pans. Line bottoms of pans with parchment paper; grease and lightly flour pans.

In a medium bowl, stir together flour, sugar, baking soda and salt. In a large bowl, stir together buttermilk, oil, eggs and vanilla. Fold in flour mixture until combined. Add cooled chocolate mixture, stirring until combined.

Divide batter among prepared pans. Bake until a toothpick inserted in centers comes out clean, 25 to 30 minutes. Cool in pans 10 minutes. Turn cakes out onto wire racks; peel off paper. Cool completely.

For filling: In a medium saucepan, combine sweetened condensed milk, sugar, egg yolks and butter. Cook and stir over medium until slightly thickened and mixture just bubbles, about 7 minutes. Stir in coconut and pecans. Cover and cool at least 1 hour before using.

For frosting: In a medium saucepan, combine butter and chopped chocolate. Cook and stir over low until chocolate is melted; transfer to a large bowl. Add half of the powdered sugar and beat with a mixer on low speed. Add remaining powdered sugar and beat on low until powdered sugar is evenly incorporated. (Mixture will be crumbly.) Add sour cream and vanilla; beat until creamy.

To assemble: Place one cake layer on a serving plate. Spread with one-third of the filling. Repeat with remaining two layers and filling, leaving a 1-inch border around the top edge. Chill cake 1 hour.

Frost sides of cake. Using a pastry bag, pipe the remaining frosting around the cake's top edge.