Preheat the oven to 350°F (175°C). Grease the bottom of two 9-inch round pans or one 9x13-inch baking dish.

Melt the German chocolate with water in the microwave for 1.5–2 minutes, stirring every minute until smooth.

In a separate bowl, whisk together the flour, baking soda, and salt.

In a large mixing bowl, beat the butter and sugar until light and fluffy. Add the egg yolks one at a time, then stir in the melted chocolate and vanilla.

Add the flour mixture and buttermilk alternately, mixing well after each addition.

In a clean bowl, beat the egg whites until stiff peaks form. Gently fold them into the batter.

Pour the batter into the prepared pans. Bake for 30 minutes, or until a toothpick comes out clean.

Cool the cakes in the pans for 15 minutes. Then remove them and let the cakes cool completely.

In a saucepan, whisk together the egg yolks, evaporated milk, and vanilla. Add sugar and butter.

Cook over medium heat, stirring constantly until thickened and golden brown. Remove from heat and stir in coconut and pecans. Let cool to spreading consistency.

Spread the frosting between the layers, on top, and around the cake.