Adjust oven rack to the center and preheat oven to 350 degrees.  Grease a 9x13 inch cake pan with butter.  Combine the cocoa, instant espresso and boiling water in a small bowl and mix until smooth.  Cool to room temperature and stir in the vanilla and buttermilk.  Beat the butter in a mixing bowl with an electric hand mixer until smooth and shiny (about 30 seconds).  Gradually sprinkle in sugar, mixing continuously, until mixture is fluffy and almost white (about 4 minutes).  Add the eggs one at a time, beating a full minute after each addition.  Whisk the flour, baking soda and salt together in a separate bowl.  With mixer on lowest setting, pour 1/3 of the flour mixture and 1/3 of the cocoa mixture into the butter mixture and beat until ingredients are incorporated into the batter.  Repeat the process twice more.  Beat until the batter looks satiny.  Pour the batter into the greased cake pan.  Bake the cake until it feels firm in the center when lightly pressed and a toothpick comes out clean (23 to 30 minutes).  Cool completely before frosting.

Coconut-Pecan Frosting.  Combine the egg yolks, sugar and salt in a mixing bowl and beat with an electric hand mixer.  Beat in the butter.  Gradually beat in the heavy cream and vanilla.  Pour the mixture into a skillet and cook over low heat, stirring constantly, until the mixture is puffy and just begins to thicken (15 to 20 minutes).  Pour the mixture into a bowl and cool to room temperature.  Stir in the pecans and coconut.  Spread the frosting on the cake.

Our comments:  Nothing beats a good German Chocolate Cake and this is a good German Chocolate Cake.  They can be dry ... but not this one.  The kids can't handle the nuts in the icing ... someday they will learn.