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5 from 5 votes

Easy Rainbow Buttercream Cupcakes

The prettiest little rainbow cupcakes you ever did see, and tasty too.
Course Dessert
Cuisine American
Keyword rainbow buttercream, rainbow cupcakes
Prep Time 20 minutes
Cook Time 23 minutes
Total Time 43 minutes
Servings 20 cupcakes
Calories 282kcal
Author Lise Ode


For the cupcakes

  • 1 box cake mix of choice prepared according to package instructions

For the frosting

  • 1 cup unsalted butter, softened
  • 4 cups powdered sugar 16 ounces
  • 1/4 cup heavy whipping cream
  • 1 teaspoon clear vanilla flavoring I use clear so it doesn't interfere with the color
  • Food coloring gel Assorted colors


For the cupcakes

  • Prepare cake mix batter according to package instructions and bake as directed. I lined two 12-cup muffins pans with cupcake liners and made 20 cupcakes (I've found that when you make 24 cupcakes from a cake mix, they come out too small). Let cool.

For the frosting

  • Beat softened butter on medium speed with an electric or stand mixer. Beat for 3 minutes until smooth and creamy.
  • Add powdered sugar, cream, and vanilla extract with the mixer running on low. Increase to high speed and beat for 3 minutes. Use immediately or store in an airtight container in the refrigerator for up to 2 weeks.
  • Note: If the frosting is too thick, you can add a little more cream. Just add one tablespoon at a time, then mix thoroughly until you get the consistency you like.
  • To color the frosting: Divide buttercream into 6 medium bowls (like the size of a cereal bowl) and color each with the desired food coloring. I made red, orange, yellow, green, blue and purple frosting using food coloring gels which I ordered online. Using traditional food coloring from the grocery store will not result in the vibrant colors you see in the photos of these cupcakes.

Decorating the cupcakes

  • Place each frosting color into a tipless pastry bag, cut a small corner and pipe lines of buttercream onto a large piece of plastic wrap placed on your counter. Roll up the plastic wrap into a cigar like shape and twist the ends. Cut off one end and place into a large pastry bag fitted with a 1M tip. Pipe swirls of rainbow frosting onto the cooled cupcakes. Serve immediately or store covered in the refrigerator up to 1 week. As in any baked goods, the taste is the best the first day.


Note: If you don't have heavy cream, you can use milk or water instead. If using milk or water, I would try 3 tablespoons instead of 1/4 cup. If it's too thick, add another tablespoon.


Calories: 282kcal | Carbohydrates: 45g | Protein: 1g | Fat: 11g | Saturated Fat: 7g | Cholesterol: 28mg | Sodium: 262mg | Potassium: 21mg | Fiber: 1g | Sugar: 34g | Vitamin A: 327IU | Calcium: 61mg | Iron: 1mg