Preheat the oven to 350 F. Line muffin pan with red cupcake liners.

In a large bowl, combine sugar, flour, baking powder, baking soda, salt, and black cocoa powder.

Add egg, milk, oil, and vanilla. Beat on medium speed until combined, about 2 minutes.

Stir in boiling water. Batter will be thin and runny.

Pour batter into the prepared muffin pan, filling each cup about ⅔ full.

Bake cupcakes for 15 minutes or until a toothpick inserted into the center comes out clean.

Cool cupcakes in the pan for 10 minutes before transferring to a wire rack to cool completely.

In a medium bowl, beat the butter and vanilla until smooth.

Add the powdered sugar and milk and beat until combined.

Beat on high speed until fluffy.

Transfer to a piping bag fitted with a medium round piping tip.

Combine the melted butter and black cocoa powder in a medium bowl.

Alternately, add the powdered sugar and milk. Beat until spreadable.

Stir in the vanilla.

Transfer to a piping bag fitted with a medium round piping tip. If you don’t have a second piping tip, leave the frosting in the bowl until you’ve finished with the vanilla buttercream. Then, clean the piping tip and transfer the frosting to a piping bag fitted with the tip.

Using an apple corer, remove the center of each cupcake. If the cupcakes feel sticky and are hard to work with, place them in the refrigerator to chill for 10-15 minutes.

Fill each cupcake with vanilla buttercream by placing the tip of the piping bag in the center of the cupcake and applying even pressure on the bag until the frosting fills the cupcake.

To decorate the cupcakes, pipe the vanilla buttercream in small dollops on half of each cupcake. To make a dollop, press the piping bag gently until the frosting comes out in a small round. Release the pressure on the bag and pull it upwards. This will pull the frosting up a little bit and make a dollop.

Next, pipe the black chocolate buttercream in small dollops on the unfrosted half of each cupcake.