Preheat oven to 350°F. Grease and flour two 9-inch round cake pans and set aside. For cake, combine dry ingredients in a small bowl and set aside. In a large bowl, mix butter, sugar and eggs until blended. Add buttermilk, mayonnaise, vanilla extract and food color and mix until smooth and uniform in color. Slowly add the dry ingredients to the wet ingredients and blend until combined. Pour into the prepared pans and bake for 30 minutes or until a toothpick inserted in the center comes out clean. For 24 cupcakes, fill cups 2/3 full and bake for 15-20 minutes or until a toothpick inserted in the center comes out clean. While the cake or cupcakes are baking, in a large bowl, combine butter, cream cheese and vanilla extract and beat until uniform and smooth. Add confectioner's sugar 1 cup at a time, beating after each cup. Cool cake completely before frosting.