Preheat the oven to 350°F (175° C). Line a muffin pan with 12 cupcake liners.
In a medium bowl, whisk together flour, sugar, cocoa powder, baking soda, baking powder, and salt.
In a stand mixer with a paddle attachment, whip the egg, sour cream, oil, and vanilla extract on medium speed until well combined, about 1 minute.
Add the dry ingredients and mix the batter until just combined, starting on low and gradually increasing the speed to medium-high, about 30 seconds.
Scrape the sides of the bowl, add hot coffee, and mix again until just combined.
Divide the batter into the prepared cupcake cups halfway full.
Bake for 15-18 minutes or until the inserted toothpick comes out clean. Cool completely.