11. Heat oven to 350° F. Line muffin cups with cooking spray. In large mixing bowl, whisk together wet ingredients.
22. In another bowl, stir together dry ingredients. Add dry ingredients to wet ingredients; beat on medium speed for 2 minutes. Stir in boiling water; mix well. Fill muffin cups ⅔ full. Bake for 22-25 minutes, or until a toothpick comes out clean. Cool on cooling rack. Frost cupcakes only when completely cooled!
33. Frosting: In large mixing bowl, beat butter and 3 cups powdered sugar for 30 seconds. Add food coloring. Add margarita mix, alternating with remaining powdered sugar; beat between each addition. If needed, add tablespoon of milk or margarita mix to develop correct texture.
44. Fill pastry bag with star tip; pipe frosting onto cooled cupcakes.