Preheat your oven to 350ºF (175ºC). Line the bottoms of two 8" x 3" round cake pans with parchment paper and grease the sides with butter to prevent sticking.

Using a stand mixer fitted with the paddle attachment, cream together the butter and sugar on medium-high speed for about 3 minutes, making sure to stop and scrape down the sides and bottom of the bowl halfway through to ensure a smooth mixture without lumps.

Add the egg yolks one at a time, mixing well after each addition. Continue mixing on medium-high speed for about 4 minutes, or until all the yolks are fully incorporated and the mixture is light and fluffy.

In a separate bowl, combine the German sweet chocolate with the boiling water, stirring until the chocolate is completely melted and smooth. Let it cool slightly, then add the melted chocolate and vanilla extract to the creamed mixture. Mix on medium speed for 3 minutes, or until everything is well blended.

In another bowl, sift together the flour, salt, and baking soda. With the mixer on medium-high speed, alternate adding the dry ingredients and the buttermilk to the chocolate mixture, starting and ending with the dry ingredients. Continue mixing for about 5 minutes, scraping the bowl again halfway through to ensure an even batter.

In a clean bowl, use the whisk attachment to beat the egg whites on high speed for about 5 minutes, or until stiff peaks form. Carefully fold the beaten egg whites into the cake batter, taking care not to deflate the mixture. Fold gently until fully combined.

Divide the batter evenly between the prepared pans and place them in the oven. Bake for approximately 45 minutes, or until a toothpick inserted into the center comes out clean.

While the cakes are baking, begin making the frosting. In a medium saucepan, combine the evaporated milk, sugar, butter, egg yolks, and vanilla extract. Stir the mixture together and cook over medium heat for about 12 minutes, or until it thickens and becomes rich and golden.

Remove the saucepan from heat and stir in the shredded coconut and chopped pecans. Mix well until everything is evenly combined. Set the frosting aside to cool completely before using it to assemble and frost the cake.

Once the cakes are fully baked and cooled, layer them with the coconut-pecan frosting. Slice, serve, and enjoy every bite of this classic homemade German Chocolate Cake!