For the German Chocolate Cake:
- Preheat the oven to 350°F. Prepare two 9-inch cake pans by spraying with baking spray or buttering and lightly flouring them.
- In the clean bowl of a stand mixer fitted with the whisk attachment (or using a hand mixer), combine the flour, sugar, cocoa, baking powder, baking soda, salt, and espresso powder. Add the milk, eggs, and vanilla and beat on medium speed until well combined. Reduce the speed to low and add the coconut oil. With the mixer still on low speed, carefully and slowly pour in the boiling water and beat until well combined, about 3 minutes. Pour the batter into the prepared cake pans.
- Bake until a wooden toothpick inserted in the center comes out clean, 30 to 35 minutes. Let the cakes cool for 10 minutes. Turn the cakes out of the pans onto wire racks and let cool completely before frosting.
- Spread the frosting on the top of one of the cake layers. Top with the second layer and frost the top only.
For the Coconut Pecan Frosting (makes 3 cups)
- In a medium bowl, beat together the egg yolks and evaporated milk and pour the mixture into a large saucepan. Add the sugar and stir until dissolved. Add the butter, set the pan over low heat, and cook, stirring constantly, until thick, 10 to 12 minutes.
- Remove the pan from the heat and add the vanilla, coconut, and pecans. Stir with a wooden spoon until thickened to a spreading consistency, about 5 minutes. Spread on the cake while the frosting is still warm.