In a large bowl, whisk together the flour, cocoa powder, baking powder, baking soda, salt, and sugar.
1 1/2 cups all-purpose flour, 2 tbsp unsweetened cocoa powder, 2 tsp baking powder, 1/2 tsp baking soda, 1/4 tsp salt, 3 tbsp granulated sugar
In a separate bowl, combine the buttermilk, whole milk, egg, melted butter, vanilla extract, and red food coloring. Mix until smooth.
1 large egg, 1 cup buttermilk, 1/4 cup whole milk, 2 tbsp melted butter, 1 tsp vanilla extract, 1/2 tbsp red food coloring
Gently fold the wet ingredients into the dry ingredients. Don’t overmix—lumps are okay! Let the batter sit for 10 minutes while you prepare the glaze.