Pre-heat oven to 350 degrees. Prepare two 9x13" baking pans by spraying with cooking spray and lining the bottom with parchment.
In the bowl of your stand mixer fitted with the whisk attachment, combine flour, sugar, cocoa, baking soda, baking powder, and salt and mix together.
Add the eggs, coffee, buttermilk, oil, and vanilla and mix on medium speed for a couple minutes.
Divide the batter between the two prepared pans. Bake for 20-25 minutes or until a tooth pick comes out with a few moist crumbs.
Allow to cool for 15 minutes in the pans and then carefully flip the cakes over to remove from the pans and transfer to a wire rack to fully cool.
Once the cakes are fully cool, level if needed and use a round cookie cutter to cut out your mini cake rounds.