Prep: Preheat oven to 350°F and line a 12 cup cupcake pan with liners.
Mix dry ingredients: Add 1 cup all-purpose flour, ½ cup unsweetened cocoa powder, 1 teaspoon baking powder, ¼ teaspoon baking soda, ¼ teaspoon fine sea salt and 1 teaspoon espresso powder to a large bowl and whisk until well combined.
Mix wet ingredients: Add ½ cup granulated white sugar, ½ cup light brown sugar, ⅓ cup vegetable oil, ½ cup buttermilk, ⅓ cup hot coffee, ½ tablespoon vanilla extract and 1 large egg to a separate bowl or measuring cup and whisk until smooth.
Add wet to dry: Add the wet ingredients to the dry ingredients and stir (no whisk! use a wooden spoon or spatula) just until combined. The batter will be thin.
Fill liners and bake: Divide the batter between the prepared cupcake liners. Bake for 20 minutes or until a toothpick inserted into the middle comes out clean. Cool in the pan for 5 minutes, then remove to a cooling rack to cool completely before adding any frosting.
Notes
Ingredient notes
Cocoa powder – Use unsweetened, not Dutch-processed, for the best rise.
Espresso powder – Enhances chocolate flavor; optional but recommended.
Buttermilk – Keeps cupcakes moist; sub with milk + ½ tsp vinegar or lemon juice.
Vegetable oil – Makes cupcakes soft; butter works but results in a denser texture.
Brown & white sugar – The mix gives the best texture; subbing all white sugar works but makes them less soft.
Recipe tips
Use hot liquid – Helps intensify chocolate flavor.
Measure flour correctly – Spoon and level; don’t scoop.
Don’t overmix – Stir until just combined; overmixing = dense/gummy cupcakes.
Fill liners ⅔ full – Prevents overflow and sinking.
Check doneness early – Start at 18 min; a toothpick should have moist crumbs, not wet batter.
Cool before frosting – Warm cupcakes = melted frosting mess.
Storage tips
Make ahead – Bake a day ahead and store in an airtight container.
Leftovers – Store frosted cupcakes at room temp (buttercream) for 2 days or refrigerate (perishable frostings).
Freezing – Freeze unfrosted cupcakes up to 3 months; thaw at room temp.