Preheat the oven to 350°F. Line a muffin pan with 12 cupcakes liners.
In the mixing bowl of a stand mixer with the paddle attachment fitted add the butter and sugar. Beat until light and fluffy, about 3 minutes.
⅓ cup unsalted butter, 1 cup granulated sugar
Add the eggs one at a time and beat until fully incorporated. You will need to scrape down the bowl a couple of times.
2 large eggs
In a small bowl whisk together cocoa powder, water, red food coloring and vanilla extract until smooth.
1½ tablespoons unsweetened cocoa powder, 3 teaspoons water, 1 teaspoon red gel food coloring, 2 teaspoons vanilla extract
Add the cocoa mixture to the beaten butter, eggs and sugar.
Beat until all the ingredients are fully incorporated. The contents of the bowl should be uniform in color.
Turn the mixer to its lowest speed and add ⅓ of the buttermilk followed by ⅓ of the flour. Repeat these steps until all the buttermilk and flour have been used up.
¾ cup buttermilk, 1¾ cups all purpose flour
Next, add the salt, baking soda and white vinegar to the cake batter and beat to combine. Do not over mix.
½ teaspoon salt, ½ teaspoon baking soda, 2 teaspoons white vinegar
Fill the cupcake liners ¾ full. Bake the cupcakes for 20 minutes, or until the tops spring back when touched with your finger and a toothpick inserted in the center comes out clean.
Leave the cupcakes to cool for a few minutes in the pan before transferring them to a wire rack to completely cool.
The cupcakes will have risen slightly over the edges of the liner. Trim the tops with a sharp serrated knife and blitz into crumbs for decorating later.