These cupcakes are great for a birthday party with a rainbow, spring, summer or "Wizard of Oz" theme. Use food coloring to make cupcakes with colored layers. Divide your batter evenly into five mixing bowls and add food coloring to each. Make a bowl of yellow, green, red, blue and purple batter or whatever shades you like. If you want bolder, darker colors, consider using gel food coloring, which yields more intense shades and doesn't dilute the batter like liquid dyes can. If you prefer more pastel hues, start by adding very little coloring and increase the tint to your desired shade. After your bowls of batter are ready, make a rainbow by spooning about a tablespoon of one color into the sections of a muffin pan, and then repeat with different layers. Bake your cupcakes, and you'll have rainbow treats ready to be frosted for your party!