Preheat your oven to 350°F (175°C) and line a standard cupcake pan with 12 cupcake liners.

In a medium-sized mixing bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt.

In a large mixing bowl, cream the softened butter and sugar together until light and fluffy.

Add the whole egg, egg yolk, and vanilla extract to the butter-sugar mixture and beat until pale and smooth.

Alternately add the dry ingredients and buttermilk to the wet mixture, then fold in the red gel food coloring.

Spoon the batter into the cupcake liners, filling each about three-quarters full.

Bake in the preheated oven for 17-20 minutes or until a toothpick comes out clean.

Remove the pan from the oven and allow the cupcakes to cool for about 10 minutes.

Prepare the cream cheese frosting by beating softened butter, then adding cream cheese, and gradually mixing in powdered sugar until smooth.

Frost the cooled cupcakes generously and top with sprinkles if desired.