Preheat oven to 350°F. Liberally butter three 9” cake pans, and tap a tablespoon of flour around in each,
until evenly coated. Line with a round sheet of parchment paper.
In a large bowl, whisk together flour, sugar, first cocoa powder,
baking powder, baking soda, and salt. In a separate bowl, whisk
together buttermilk, eggs, and vegetable oil. Add the liquid ingredients
to the dry, and whisk until smooth. Divide evenly between the cake pans,
and bake for 30-35 minutes, or until a tester comes out clean. Place pans
on racks to cool for at least 30 minutes before flipping onto racks, and allowing
to cool completely, another 30-60 minutes.
While cakes cool, beat together butter and cream cheese in the bowl of a stand mixer
using the paddle attachment. Once fluffy, add cocoa powder, and mix until combined.
A cup or two at a time, add powdered sugar, and beat until creamy and smooth.
Add a splash of milk if desired to adjust consistency.
Slice the rounded tops off each layer of the cake, frost, slice, and serve.