Preheat your oven to 350°F (175°C) and prepare three 9-inch round cake pans by greasing them and lining the bottoms with parchment paper.

In a large mixing bowl, whisk together the flour, granulated sugar, brown sugar, cocoa powder, baking powder, baking soda, and salt.

In another bowl, combine the buttermilk, vegetable oil, eggs, and vanilla extract. Beat the mixture until smooth.

Gradually add the wet ingredients to the dry ingredients, mixing until well combined. Carefully stir in the boiling water.

Pour the batter evenly into the three prepared cake pans.

Bake in the preheated oven for about 35-40 minutes, or until a toothpick inserted into the center comes out clean.

Once baked, allow the cakes to cool in the pans for about 10 minutes before transferring them to a wire rack to cool completely.

In a saucepan over medium heat, combine coconut, chopped pecans, and the melted German chocolate. Stir for a few minutes until heated through, then remove from the heat and let it cool.

Once the cakes are completely cool, layer them with the coconut-pecan frosting between the layers and on top.

Cut into slices and serve!