Preheat the oven to 350 (F).

Put the flour, cocoa powder, sugar, baking powder, salt, and butter in a freestanding electric mixer with a paddle attachment and beat on slow speed until you get a sandy consistency and everything is combined.

Whisk the milk, egg, and vanilla together in a pitcher, then slowly pour about half into the flour mixture. Beat to combine and turn the mixer up to high speed to get rid of any lumps.

Turn the mixer down to a slower speed and slowly pour in the remaining milk mixture, making sure to scrape any unmixed ingredients from the side of the bowl with a rubber spatula. Continue mixing for a couple more minutes until the batter is smooth, but do not overmix.

Spoon the batter into paper cases until two-thirds full and bake in the preheated oven for 22-26 minutes, or until the cake tops bounce back when touched. A skewer inserted in the center should come out clean when the cupcakes are cooked.

Let the cupcakes cool slightly in the muffin pan before turning out into a wire rack to cool completely.

When the cupcakes are cold, spoon the chocolate frosting on top and decorate accordingly.

Beat the confectioners’ sugar, butter, and cocoa together in a freestanding electric mixer with a paddle attachment on medium-slow speed until the mixture is well mixed.

Turn the mixer down to a slower speed and add the milk to the butter mixture a couple of teaspoons at a time.

Once all the milk has been incorporated, turn the mixer up to high speed. Continue beating until the frosting is light and fluffy; this should take at least 5 minutes.