Prepare the pans. Preheat the oven to 350°F (175°C). Grease two 9-inch round cake pans and line the bottoms with parchment paper.

Combine the dry ingredients. Add the flour, granulated sugar, cocoa powder, baking soda, baking powder, and salt to a large mixing bowl. Whisk until everything is evenly distributed.

Mix in the wet ingredients. Add the eggs, buttermilk, vegetable oil, and vanilla extract. Beat or whisk until the batter is smooth and no dry streaks remain.

Add the hot liquid. Gradually pour in the hot coffee or hot water while mixing gently. The finished batter will be fairly thin, which is normal.

Bake the cake layers. Divide the batter evenly between the prepared cake pans. Bake for 28 to 32 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs.

Cool completely. Leave the cakes in their pans for about 10 minutes. Carefully turn them onto wire racks and allow them to cool completely before frosting.

Cook the coconut pecan frosting. Combine the evaporated milk, granulated sugar, egg yolks, and butter in a saucepan over medium heat. Cook for 10 to 12 minutes, stirring constantly, until the mixture becomes noticeably thick.

Finish the frosting. Remove the saucepan from the heat and stir in the vanilla extract, shredded coconut, and chopped pecans. Set the frosting aside until completely cooled and thick enough to spread.

Make the optional chocolate frosting. Beat the softened butter until creamy, then gradually mix in the powdered sugar and cocoa powder. Add the vanilla and enough milk to create a smooth, spreadable frosting.

Assemble the cake. Place the first chocolate cake layer on a cake plate or serving stand. Spread approximately half of the coconut pecan frosting evenly over the top.

Add the second layer. Carefully position the remaining cake layer over the first. Spread the rest of the coconut pecan frosting generously across the top.

Decorate if desired. Spread or pipe the optional chocolate frosting around the sides of the cake. Leave the coconut pecan topping visible for the traditional German Chocolate Cake appearance.

Serve. Allow the assembled cake to settle briefly before slicing. Cut into wedges and serve at room temperature or slightly chilled.