Preheat oven to 325º F.

Spray inside of 2 round 8 inch cake pans with baking spray. If you use parchment rounds, place in pan and spray the parchment as well.

Measure all dry ingredients into the bowl of a stand mixer. Mix dry ingredients with a whisk to blend.

Add buttermilk, vegetable oil, egg, and vanilla to dry mixture on medium speed until well combined.

Reduce speed and carefully add boiling water to the cake batter. Beat on high speed for about 1 minute to add air to the batter.

Pour half the batter into each pan. Bake for 25 minutes on the middle rack, turning pans half way. Test doneness by inserting a toothpick into the center of the cake. If it comes out clean, cake is done.

Allow cakes to cool in pans for 10 minutes.  At this point, remove cakes from pan and allow to cool completely on a wire rack.

While cake cools, make the buttercream frosting.

Add cocoa to bowl of stand mixer. Using a whisk or fork, get rid of any lumps.

Cream butter and cocoa powder until combined. Turn off mixer.

One cup at a time, add in the confectioner’s sugar and about a teaspoon of the cream. Slowly bring mixer up to speed to avoid the sugar from flying out of the bowl. Between each addition, bring up to fast speed to fully whip the frosting. Repeat until all the sugar and cream are added. Add vanilla extract and espresso powder and combine well.

At this point, check the consistency of the frosting. If too stiff, add a bit more of the cream, and beat until fluffy.

Using a serrated knife or cake leveler, remove the top rounded portion so that they are level. Place first cake on plate, add frosting and smooth out. Add next cake and frost top and sides.