Preheat oven to 325°. Brew one cup of coffee and set aside cup of black coffee and let cool to room temperature. Do not add in sugar or cream, coffee must be black and room temp. Prep 8-inch cake pans by spreading 1 tsp of butter on the inner walls and bottom of each pan. Then dust with 2 tbs of flour to coat each pan. Tap pan to coat evenly and discard any extra.
In a bowl, combine sugar and oil with mixer. In a separate bowl, sift flour, cocoa powder, salt, baking soda, and baking powder. In a third separate bowl, mix buttermilk, vinegar, coffee, and vanilla. In a separate bowl with mixer on low, incorporate eggs 1 at a time the bowl of oil & sugar mixture.
Alternate adding dry mixture & butter milk mixture into sugar, oil, and egg mixture until they are combined and well incorporated.
Divide batter between the two pans evenly. Bake for 35 min or until you insert a tooth pick and it is removed without any batter residue.
Cool then add frosting.
*Tip: Add round cut parchment paper to prepped pans prior to adding batter for easier cake removal.