Preheat the Oven
Preheat the oven to 325°F (165°C) and prepare the cake pans.
Mix Cocoa + Coffee
In a small bowl, combine the cocoa powder with hot coffee or water. Let it sit briefly.
Combine Dry Ingredients
In a separate bowl, mix the flour, baking powder, baking soda, salt, and optional cinnamon.
Mix Wet Ingredients
In a large bowl, combine the sugar, vegetable oil, melted butter, eggs, egg yolk, buttermilk, vanilla extract, and red food coloring.
Add Vinegar + Cocoa Mix
Stir in the vinegar and the prepared cocoa mixture until combined.
Add Dry Ingredients Gradually
Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Divide Batter
Evenly divide the batter between the prepared cake pans.
Bake
Bake for 25–30 minutes, or until the cakes are set.
Course: Dessert
Cuisine: American