Step 1: Preheat your oven to 350°F (175°C). Grease and flour three 9-inch round cake pans.
Step 2: In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy, about 3-4 minutes.
Step 3: Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
Step 4: In a separate bowl, whisk together the flour, cocoa powder, baking soda, baking powder, and salt.
Step 5: Gradually add the dry ingredients to the wet mixture, alternating with the buttermilk. Begin and end with the dry ingredients, mixing until just combined.
Step 6: Divide the batter evenly among the prepared cake pans.
Step 7: Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted in the center comes out clean.
Step 8: Allow the cakes to cool in the pans for 10 minutes before transferring them to wire racks to cool completely.
Step 9: In a medium saucepan, combine the granulated sugar, evaporated milk, butter, and egg yolks. Cook over medium heat, stirring constantly until the mixture thickens and begins to boil, about 10 minutes.
Step 10: Remove from heat and stir in the vanilla extract, shredded coconut, and chopped pecans. Let the frosting cool to room temperature.
Step 11: Once the cakes are completely cooled, place one layer on a serving plate. Spread a generous amount of the coconut-pecan frosting on top.
Step 12: Add the second layer of cake and repeat the frosting process. Place the final layer on top and spread the remaining frosting over the top and sides of the cake.
Step 13: Slice the cake and serve. Enjoy your homemade German Chocolate Cake!