In your bowl of water, espresso powder, and black cocoa, add and mix together your granulated sugar, vanilla extract, eggs, buttermilk, distilled white vinegar, and oil.
A third at a time, add your dry ingredients to your large bowl of wet ingredients. Mix and scrape the sides of the bowl until all ingredients are fully combined.
Pour and evenly spread the cupcake batter into your prepared cupcake liners. Bake for 16-18 minutes or until cupcakes bounce back at the touch of your finger.