You can make your own buttermilk by adding a tablespoon of distilled white vinegar to milk and letting it stand for about 10 minutes.
1 Preheat the oven to 350°F. Line a muffin tin with cupcake papers.
2 Make the cupcake batter: Beat the butter and sugar in an electric mixer for 3 minutes on medium speed until light and fluffy.
Add the eggs, one at a time, beating until each is fully incorporated. Be sure to scrape down the sides of the bowl to ensure even mixing.
In a large bowl, sift together the cake flour, cocoa powder, baking soda, baking powder, and salt. In another bowl whisk together the buttermilk, vinegar, vanilla extract, and red food coloring.
Add a fourth of the dry ingredients and mix, then add a third of the wet. Continue adding in a dry, wet, dry pattern, ending with…