Preheat Oven to 350 degree and line cupcake pan with cupcake liners
In a large bowl, add together the flour, cocoa powder, baking powder, baking soda, and salt, mix to combine
Add in the sugar and brown sugar stir until combined.
Add the oil, buttermilk, egg, and vanilla extract. Stir until combined.
Fill cupcake liner 3/4 of the way full.
Bake for 21 minutes.
Remove the cupcakes from the oven.
Transfer the cupcakes to a wire rack to cool