• Preheat oven to 350F and line a muffin tin with muffin tin liners (you will be making 10 cupcakes)
• In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking soda, baking powder, and salt. Set aside.
• In a separate bowl, combine the buttermilk, vegetable oil, egg, and vanilla extract. Whisk well.
• Add the wet ingredients to the dry ingredients and fold together. When there are still a few streaks of dry flour remaining, add the hot coffee, and fold everything together until just combined.
• Divide the batter evenly into the muffin tins.
• Bake for about 20-25 minutes. They will rise and spread out a bit, but this is fine.
• Remove from the oven and allow to cool completely on a rack before proceeding.

to make the frosting

• Add the room temperature butter and powdered sugar to a large capacity food processor (you can also use a stand mixer) and blend until smooth. Add the sour cream, salt, and vanilla extract, and blend again until smooth.

to assemble the cakes

• Remove the cupcakes from their cupcake liners. Take a cupcake and place it upside down. Using a 3 inch biscuit cutter, trim away the excess cake, forming a cylinder.
• Using a serrated knife, gently cut the trimmed cake into 2 even layers. Repeat for the remaining cupcakes.
• Place about a tablespoon or so of frosting onto one of the cake layers, and place the second layer on top. Repeat for the remaining cakes so that you have 10 2-layer mini cakes.
• For this cake recipe, I recommend doing a quick "crumb coat" of frosting because the cakes are soft and moist. Using a butterknife or a small silicone spatula, frost the cakes with a thin coat of frosting. It will be a little fiddly, but do your best! Chill in the fridge for 20-30 minutes to let them firm up.
• Frost the cakes with a second layer of frosting. It should be much easier this time with the crumbs "locked in" to the crumb coat. Top with sprinkles if desired.