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Two cupcakes decorated with rainbow-colored frosting and topped with mini marshmallows, placed on a wire cooling rack.
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5 from 41 votes

Rainbow Cupcakes

The perfect way to celebrate any occasion! These rainbow cupcakes are light, and sweet, and give a pop of color to any dessert table!
Prep Time45 minutes
Cook Time14 minutes
Cooling Time1 hour
Total Time2 hours 10 minutes
Course: Dessert Recipes
Cuisine: American
Servings: 18 cupcakes
Calories: 407kcal
Author: Laura

Equipment

  • cupcake pan
  • piping bags 7
  • plastic wrap
  • large star tip if using Wilton use 1 M large tip or any large star tip will work
  • cup cake liners

Ingredients

For Cupcakes

  • ½ c unsalted butter softened
  • 1 ⅔ c sugar
  • 6 egg whites
  • 1 t vanilla
  • ¼ c oil
  • 1 ¼ c milk
  • ½ t salt
  • 2 ½ t baking powder
  • 2 c flour

For Frosting

  • 1 c unsalted butter softened
  • 1 t vanilla
  • 1 t salt
  • 4 c powdered sugar
  • 3 T milk
  • Food coloring purple, blue, pink, orange, yellow, green
  • Mini marshmallows to decorate as clouds

Instructions

  • Preheat the oven to 350 degrees 
  • Put liners in the cupcake pan and set aside.
  • In the bowl of a stand mixer, combine the softened butter and sugar, cream until smooth.
  • Add in the egg whites, oil and vanilla, mix well
  • Add the milk and mix to combine, it may look lumpy but trust the process
  • in a small bowl mix in the salt, baking powder and flour
  • Add in the flour mix to the butter mixture and stir on low to combine, stop the machine, scrape down the sides and mix again
  • Measure out the batter and fill each cavity until about ½-⅔ full.  Bake in the preheated oven for approximately 14 minutes or until the cupcakes are golden brown and the center is set.  Allow the cupcakes to cool completely before decorating
  • For the frosting - in the bowl of a stand mixer, combine the butter, vanilla, salt and about half of the powdered sugar
  • Mix on low speed until combined.  Add in the remaining powdered sugar and the milk. Mix on low speed until combined
  • Once combined, bump up the speed to medium for an additional minute until the frosting is fluffy and smooth
    A bowl containing a mixture of ingredients, likely a batter or dough, on a marbled surface.
  • Divide the frosting - measure out ½ of a cup of frosting into separate small bowls for each of the colors you'll be using
  • tint each bowl of the frosting a different rainbow color
    Seven bowls of variously colored frosting (purple, orange, green, blue, yellow, and pink) aligned next to a piping bag filled with white frosting, all set on a marble surface.
  • The remaining frosting will stay white and it can be transferred to a piping bag. 
  • Line out a strip of plastic wrap approximately 18-24 inches long.  Pipe each color onto the plastic wrap in rainbow order - purple, blue, green, yellow, orange and then pink
    Multicolored stripes of playdough aligned side by side on a plastic surface.
  • Roll the plastic wrap and coloring frosting so that they overlap.  Place the log of frosting into a piping bag fitted with a large star-tip
    A multicolored cylindrical object, possibly clay or dough, wrapped tightly in clear plastic film, set against a neutral-toned background.
  • To decorate - once the cupcakes are cool, pipe a small mound of white frosting onto each cupcake.  Use a butter knife or offset spatula to spread and flatten the frosting to the edges
    A selection of frosted cookies on a cooling rack with a bowl of mini marshmallows and a piping bag filled with pink icing nearby.
  • Use the colored frosting bag to create an inverted “U” or horseshoe shape.  Twist the piping bag mid squeeze to show all the colors and add dimension.
    A pastry bag filled with rainbow-colored frosting, with its metal tip visible, against a white background.
  • Immediately place the mini marshmallow “clouds” before the frosting crusts over
    Rainbow cupcakes with marshmallows on a cooling rack.

Notes

Storage: Cupcakes should be stored in an airtight container in the fridge for up to 3 days or frozen for 3 months.

Nutrition

Serving: 1 cupcake | Calories: 407kcal | Carbohydrates: 57g | Protein: 3g | Fat: 19g | Saturated Fat: 10g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 6g | Trans Fat: 1g | Cholesterol: 43mg | Sodium: 280mg | Potassium: 67mg | Fiber: 0.4g | Sugar: 46g | Vitamin A: 504IU | Calcium: 65mg | Iron: 1mg