Preheat oven to 350 degrees F and grease two 9x2-inch round cake pans with butter and flour or cooking spray and line the bottoms with parchment paper. For best results, use bake-even strips.In a large bowl or stand mixer fitted with a whisk attachment, whisk together the sugar, flour, cocoa powder, baking soda, baking powder, and salt.

Beat in eggs, buttermilk, espresso, oil, and vanilla and beat on medium speed for 2 minutes, the batter is going to be very thin.

Divide the batter evenly between the two prepared 9-inch pans.

Bake the cakes for 40 to 45 minutes until a toothpick comes clean from the center.

While the cakes are baking, begin preparing your frosting since it will also need to cool for 1 hour.

Cool the cakes in pans for at least 10 minutes and loosen from the sides of the pans before transferring to a cooling rack to cool completely, about 1 hour.

After the cakes have cool and the frosting has been prepared according to the recipe directions, place one of the cake layers on a cake stand or serving plate.

 Pipe or spread a thick layer of the frosting all over the top of the layer to create the filling layer.

Top with the other cake layer and give it a crumb coat and chill for 30 minutes before adding the final coating of frosting.