Gather your ingredients. Heat oven to 180C degrees. Line a cupcake pan with paper liners.
Combine the flour, sugar, cocoa powder, baking powder, baking soda, and salt together in a bowl and whisk together.
Combine the egg, buttermilk, oil, and vanilla in another bowl and whisk together.
Add the wet ingredients to the dry ingredients and mix using a stand/hand mixer until combined.
Add the hot water/coffee to the batter and mix again, scraping the sides of the bowl as necessary, until combined. Batter will be thin.
Fill cupcake liners only 1/2 full, then bake for 18-21 minutes, until the tops bounce back when you touch them with a finger or a toothpick comes out with only a few moist crumbs when used to test a cupcake.
Cool completely before frosting.
