Preheat oven to 300°F (148°C) and prepare two cupcake pans with liners.
Add the dry ingredients to a large bowl and whisk together. Set aside. Combine the egg, buttermilk, vegetable oil and vanilla in another bowl.
Add the wet ingredients to the dry and mix until well combined. Add the hot coffee or hot water to the batter and mix until well combined. Batter will be thin.
Fill the cupcake liners just a little above halfway (transfer the batter to a bowl with a spout or a large measuring cup to make this easier) and bake for 18-23 minutes, or until a toothpick comes out with a few moist crumbs and the top springs back when lightly pressed.
Remove the cupcakes from oven and allow to cool enough so they hold their shape (about 10 minutes) then remove to a cooling rack to finish cooling.
Keywords: Buttermilk, Cake, Chocolate, chocolate cupcakes, Coffee, cupcakes, Desserts