-
Preheat the oven to 350 degrees. Line 12 muffin cups with cupcake liners and set pan aside.
-
Combine the flour, sugar, cocoa powder, baking soda, and salt in a large mixing bowl and beat with an electric mixer to combine.
-
Add the egg and beat on low just to combine. Add the coffee, sour cream, vegetable oil, and vanilla and beat to combine. Use a rubber spatula to scrape down the sides and bottom of the bowl, then beat on medium speed until batter is smooth. It will be very thin.
-
Fill each cupcake liner about 2/3 full of batter. Bake cupcakes 16 to 20 minutes, until the cake spring back when lightly touched with your fingertip.
-
Cool cupcakes in pans set on wire racks for 20 minutes, then remove from the pans to cool completely.