1. **Preheat:** Preheat oven to 350°F (175°C). Grease and flour three 9-inch round cake pans. Line the bottoms with parchment paper.

2. **Melt Chocolate:** In a small saucepan or microwave-safe bowl, melt the German sweet chocolate with the ½ cup water. Stir until smooth and set aside to cool.

3. **Mix Dry Ingredients:** In a medium bowl, whisk together the flour, baking soda, and salt.

4. **Cream Butter & Sugar:** In a large bowl or stand mixer, beat the softened butter and 2 cups sugar until light and fluffy (about 3 minutes). Beat in the 4 egg yolks, one at a time. Stir in the melted chocolate and vanilla.

5. **Combine Batter:** Add the flour mixture and buttermilk alternately to the batter (begin and end with flour), beating on low speed just until combined.

6. **Whip Egg Whites:** In a separate clean bowl, beat the 4 egg whites until stiff peaks form. Gently fold the egg whites into the cake batter until no white streaks remain.

7. **Bake:** Divide the batter evenly among the three prepared pans. Bake for 30–35 minutes, or until a toothpick inserted into the center comes out clean.

8. **Cool:** Cool in pans for 10 minutes, then turn out onto wire racks to cool completely.

9. **Make Frosting:** In a medium saucepan, combine the evaporated milk, 1 cup sugar, 3 egg yolks, and ½ cup butter. Cook over medium heat, stirring constantly, until the mixture thickens and turns golden (about 10–12 minutes).

10. Remove from heat. Stir in the vanilla, coconut, and pecans. Let the frosting cool until it is thick and spreadable (about 30 minutes).

11. **Assemble:** Place one cake layer on a serving plate. Spread ⅓ of the frosting over the top. Repeat with the second and third layers. (Traditionally, the sides are left bare to show off the layers).

12. Chill for 30 minutes before slicing to set the frosting.