Prep your pan: Heat oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners. Lightly mist the liners with baking spray for easy release.
Whisk dry ingredients: In a large bowl, whisk flour, sugar, cocoa, baking powder, baking soda, and salt until evenly combined and lump-free.
Mix the wet ingredients (except coffee): In a separate bowl or large measuring cup, whisk buttermilk, oil, eggs, and vanilla until smooth.
Combine: Pour the wet mixture into the dry ingredients.
Whisk gently just until mostly blended. The batter will be thick at this point.
Add hot coffee: Slowly pour in the hot coffee while whisking. The batter will become thin and glossy.
Stop mixing as soon as it’s uniform.
Fill the cups: Divide the batter evenly among the liners, filling each about two-thirds full. A large cookie scoop makes this tidy.
Bake: Bake 16–19 minutes, rotating the pan once halfway through. They’re done when a toothpick comes out with a few moist crumbs, not wet batter.
Cool: Let cupcakes cool in the pan for 5 minutes, then transfer to a wire rack to cool completely before frosting.
Frost and finish: Swirl with your favorite frosting.
For extra shine and flavor, add a sprinkle of flaky salt or chocolate shavings on top.