These Rainbow Cupcakes have layers of vibrant rainbow colors inside and are topped with a cloud-like swirl of vanilla buttercream. Made from a one-bowl doctored box mix recipe, they are incredibly easy to make. The perfect treat for St. Patrick’s Day, Pride celebrations, birthday parties, or any occasion in need of a little color and a lot of flavors.
Starting with a box cake mix creates a foolproof formula that allows extra time to color the batter, which requires a little extra mixing, but won’t cause the batter to be over-mixed like some cake recipes. The end result is a fluffy cupcake with bright colors and a nostalgic vanilla flavor. The best part is the sour candy on top, but the versatility of the design is what makes these so fun.
Table of contents
Rainbow Cupcake Ingredients
Box Cake: A doctored box mix recipe makes a quick solution to a homemade cake. It really is foolproof, even if something is scaled incorrectly, the outcome is still a delicious cake. It’s very stable and allows you to play with and alter the batter, like adding colors.
Flour: Adding a little extra flour gives the box cake a little more structure, so it has a tighter crumb and can handle different kinds of frostings as well as stacking if you wish.
Gel Colors: Using concentrated gel color reduces the amount of liquid you are adding to the batter, if all you have is a liquid color, that will work too, just try not to add more than 2 Tablespoons of liquid color to each bowl of batter. I like to use ChefMaster or Americolor for my gel colors, but there are many good brands that are easy to find.
Easy Buttercream is a delicious, easy, and versatile frosting. You can color this as well if you would like. Cream cheese frosting, ermine buttercream, or even a whipped ganache will also pair well if you are feeling fancy!
Making Rainbow Cupcakes
- Preheat the oven to 350° F and prepare 2 cupcake pans with paper cupcake liners.
- Add the cake mix, flour, sugar, salt, sour cream, melted butter, eggs, and milk to the bowl of a stand mixer. You can also use a large bowl and a hand mixer.
- Combine all of the dry ingredients and the wet ingredients on low speed and then mix on medium speed for 2 minutes.
- Divide the batter into 6 separate bowls.
- Using your preferred food color, color each of the small bowls in red, orange, yellow, green, blue, and purple to your desired shade of cake. The color will be more vibrant when baked. Pro-Tip: Make sure to use gel food coloring like ChefMaster or Americolor instead of liquid for more vibrant colors.
- Starting with the purple batter, either pipe or spoon about 1-1.5 tablespoons of batter into each cupcake cup. Layer each colored batter on top of the last. Try to spread the batter to the edges so you can see the rainbow through the cupcake paper.
- Place the cupcakes into the oven and bake for about 15 minutes. Make sure the center of the cupcake is done so it doesn’t sink when it cools.
- Cool the cupcakes for 5 minutes in the pans, then remove and place them on a cooling rack to fully cool. This way the bottoms of the cupcake don’t get wrinkly from the steam.
Making Easy Buttercream
- First, place the egg whites and the powdered sugar in a stand mixer bowl. Attach the whisk and combine the ingredients on low, and then whip them on high for 4 to 5 minutes (until shiny) to dissolve the powdered sugar.
- Then, add the salt and the vanilla extract.
- Next, add in your softened butter piece-by-piece, and whip it with the whisk attachment for 8 to 10 minutes until white and fluffy. When it no longer tastes buttery, it’s done!
- Finally, switch to a paddle attachment and mix the buttercream on low speed for up to 15-20 minutes. This step is optional but if you want really creamy and bubble-free frosting, you don’t want to skip it.
Assembling the Cupcakes
- Prepare a pastry bag with easy buttercream and a large star tip. Pipe a swirl of vanilla buttercream frosting on top of each cupcake. Pro-tip: If you do not have a piping bag, you can use a Ziploc bag.
- Cut the rainbow strip candy into 3-inch portions. Place the rainbow on top of the cupcake in an arch.
- Add gold or rainbow sprinkles in any design you desire to the top of each cupcake.
- To store the cupcakes, place them in an airtight container and store them at room temperature for up to 4 days. You can freeze unfrosted cupcakes or frosted cupcakes for up to a month.
FAQ
The less you touch the rainbow cupcake batter once it’s in the cup the less likely it will mix with the surrounding colors. I found that piping the colors was easier to distribute the batter around the cup evenly. However, if you do want a tie-dye effect, you can drag a skewer through the layered colors for a very fun cupcake.
Yes, we are using a vanilla box mix, and adding the food coloring doesn’t change the flavor. This recipe doesn’t call for extra vanilla extract because the box mix already has it included. You could enhance the base recipe with other flavors like lemon, coconut, almond, or clear food extract will work!
Color the easy buttercream in red, orange, yellow, green, blue, and purple. Lay out a sheet of plastic wrap and pipe the first color in a long strip along the plastic. Repeat this with each color, placing them immediately next to each other. Roll the plastic up lengthwise and place the entire buttercream bullet inside a piping bag with a piping tip.
Related Recipes
Rainbow Cupcakes
Ingredients
Rainbow Cupcakes
- 1 box white cake mix I like Duncan Hines
- 1 cup (5 oz) all purpose flour
- 1 cup (7 oz) granulated sugar
- 1/4 teaspoon salt
- 1 cup (9 oz) sour cream room temperature
- 1/2 cup (4 oz) unsalted butter melted
- 1 cup (8 oz) milk room temperature
- 3 large eggs room temperature
- 6 bottles gel food coloring: red, orange, yellow, green, blue, purple 2-3 tsps of each color
Easy Vanilla Buttercream
- 6 ounces pasteurized egg whites (from a box)
- 24 ounces powdered sugar
- 1 Tablespoon vanilla extract
- 1/2 teaspoon salt
- 24 ounces unsalted butter softened
Equipment
- 2 cupcake pans
- 24 cupcake liners
Instructions
Making Rainbow Cupcakes
- Preheat the oven to 350° F and prepare 2 cupcake pans with paper cupcake liners.
- Add the cake mix, flour, sugar, salt, sour cream, melted butter, eggs, and milk to the bowl of a stand mixer. You can also use a large bowl and a hand mixer.
- Combine all of the dry ingredients and the wet ingredients on low speed and then mix on medium speed for 2 minutes.
- Divide the batter into 6 separate bowls.
- Using your preferred food color, color each of the small bowls in red, orange, yellow, green, blue, and purple to your desired shade of cake. The color will be more vibrant when baked. Pro-Tip: Make sure to use gel food coloring like ChefMaster or Americolor instead of liquid for more vibrant colors.
- Starting with the purple batter, either pipe or spoon about 1-1.5 tablespoons of batter into each cupcake cup. Layer each colored batter on top of the last. Try to spread the batter to the edges so you can see the rainbow through the cupcake paper.
- Place the cupcakes into the oven and bake for about 15 minutes. Make sure the center of the cupcake is done so it doesn’t sink when it cools.
- Cool the cupcakes for 5 minutes in the pans, then remove and place them on a cooling rack to fully cool. This way the bottoms of the cupcake don't get wrinkly from the steam.
Easy Vanilla Buttercream
- First, place the egg whites and the powdered sugar in a stand mixer bowl. Attach the whisk and combine the ingredients on low, and then whip them on high for 4 to 5 minutes (until shiny) to dissolve the powdered sugar.
- Then, add in the salt and the vanilla extract.
- Next, add in your softened butter piece-by-piece, and whip it with the whisk attachment for 8 to 10 minutes until white and fluffy. When it no longer tastes buttery, it's done!
- Finally, switch to a paddle attachment and mix the buttercream on low speed for up to 15-20 minutes. This step is optional but if you want really creamy and bubble-free frosting, you don't want to skip it.
Assembling the Cupcakes
- Prepare a pastry bag with easy buttercream and a large star tip. Pipe a swirl of vanilla buttercream frosting on top of each cupcake. Pro-tip: If you do not have a piping bag, you can use a Ziploc bag.
- Cut the rainbow strip candy into 3-inch portions. Place the rainbow on top of the cupcake in an arch.
- Add gold or rainbow sprinkles in any design you desire to the top of each cupcake.
- To store the cupcakes, place them in an airtight container and store them at room temperature for up to 4 days. You can freeze unfrosted cupcakes or frosted cupcakes for up to a month.
Notes
- For the best rise, fill your liners 2/3 with cupcake batter or 1 1/2 ounces per cupcake
- Make sure all your ingredients are at room temperature before mixing your batter (milk, butter, eggs).
- Use clear vanilla extract for that “classic grocery store cake” flavor. Use good quality vanilla extract, vanilla bean paste, or even a vanilla bean for true vanilla flavor. One vanilla bean = 2 teaspoons vanilla extract.
- Preheat your oven to 350ºF for 30 minutes before baking to give your cupcakes a good rise and set the dome.
- Baked cupcakes can be frozen for up to 6 months.
- If you don’t have a paddle attachment, mix by hand with a spatula to avoid overmixing.