Mix dry ingredients. In the bowl of your mixer, add the flour, sugar, cocoa, baking powder, baking soda, and salt. Mix this mixture on low until combined.
Add wet ingredients. In a separate bowl, combine the buttermilk, oil, eggs and vanilla. Add the wet ingredients to the dry ingredients
Pour in the hot coffee.
Bake. Pour the batter into two prepared pans. I used 9-inch pans. Bake in a preheated 350-degree oven for 30 to 40 minutes or until a toothpick comes out clean.
Let set. Cool in the pans for 30 minutes and then turn them out on a cooling rack to finish cooling.
Make buttercream frosting. Cream together the butter and sugar. Gradually add the cocoa powder. Really, add it slowly or you and your kitchen will be wearing it.
Finish frosting. Add just enough cream so that the consistency of the frosting is spreadable. Add the vanilla. Yum.
Ice your cakes. Spread frosting in an even layer on the surface of both cakes.
Decorate. Write your birthday message.
And last but not least, decorate the edges with piping or do your own thing.