Preheat the oven to 325 (F).
Put the butter and sugar in a freestanding electric mixer with a paddle attachment (or use a handheld electric whisk) and beat on medium speed until light and fluffy and well mixed. This creaming process should take about 5 minutes at sea-level, and around 3 minutes at high-altitude.
Turn the mixer up to high speed, slowly add the egg, and beat until everything is well incorporated. Do not overbeat -- this should only take about a minute.
-
In a separate bowl, mix together the cocoa, red food coloring, and vanilla to make a thick dark, paste.
Add to the butter mixture and mix thoroughly until the batter just becomes evenly combined and colored, scraping any unmixed ingredients from the side of the bowl with a rubber spatula. Do not mix any longer than necessary.
Turn the mixer down to slow speed and slowly pour in half the buttermilk. Beat until just mixed, and then add half the flour (1/2 cup plus 1 tablespoon) and continue mixing until the flour is just incorporated.
Scrape down the side of the bowl and repeat this process until all the buttermilk and flour have been added.
Add the salt, baking soda, and vinegar one at a time. Turn the speed up to medium-high speed, and beat for about a minute.
Use a measuring spoon to dole out about 1 3/4 - 2 tablespoons of batter into cupcake cases in your muffin tin. The cases should be around two-thirds full.
Bake in the preheated oven for 20 - 25 minutes, or until the cupcake top bounces back when touched. A toothpick inserted in the center should come out clean. Let the cupcakes cool slightly in the pan before removing them onto a wire rack to cool completely.
When the cupcakes are cold, measure out approximately 1 tablespoon of cream cheese frosting on top of each cupcake and decorate accordingly.