Make the Cupcakes:

1. Preheat oven: Preheat your oven to 350°F (175°C). Line a 12-cup muffin tin with cupcake liners.
2. Mix dry ingredients: In a large mixing bowl, whisk together flour, sugar, cocoa powder, baking soda, baking powder, and salt until well combined and no lumps remain.
3. Mix wet ingredients: In a medium bowl, whisk together the egg, buttermilk, oil, and vanilla extract until smooth and well combined.
4. Combine: Pour the wet ingredients into the dry ingredients. Whisk gently until just combined – the batter will be thick at this point. Don’t overmix!
5. Add hot liquid: Carefully pour in the hot coffee (or water) while whisking gently. The batter will become very thin and liquid – this is perfect! The thin batter creates incredibly moist cupcakes.
6. Fill cupcake liners: Divide the batter evenly among the 12 cupcake liners, filling each about ⅔ full. An ice cream scoop or ¼ cup measure works perfectly for this.
7. Bake: Bake for 18-22 minutes, until a toothpick inserted into the center comes out clean or with just a few moist crumbs. The tops should spring back when lightly touched. Don’t overbake!
8. Cool: Let cupcakes cool in the pan for 5 minutes, then transfer to a wire cooling rack to cool completely before frosting. This is important – frosting warm cupcakes will cause it to melt!