Rainbow Cupcakes with Vanilla Buttercream

Rainbow Cupcakes with Vanilla ButtercreamI don’t always get into the St. Patrick’s Day spirit, but this year I decided to change that. Since I’m in charge of planning activities for a group of girls from our church I almost always need bake a treat to eat afterwards. Now that it’s March, these rainbow cupcakes with vanilla buttercream seemed perfect! I made a similar version of these rainbow cupcakes a few years back, however I was in a pinch for time and decided to use a box mix. It’s the same process, but I prefer using my own vanilla cupcake recipe because they taste so much better! And as you can probably tell, the photo needed a little update too!Rainbow Cupcakes with Vanilla ButtercreamTo begin you’ll want to go ahead and mix up the cupcake batter. Like I mentioned above, I really love this scratch recipe. Just like any cake recipe you have to start by creaming the butter and sugar until it gets nice and fluffy. I like to beat mine on high until it gets pale and doubles in size. Usually this takes about 2-3 minutes with my stand mixer, however, the time may vary a bit if you are using a hand mixer. Next add in vanilla extract (even better vanilla bean paste) and eggs. Combine all of the dry ingredients in a small mixing bowl, whisk them or sift them to remove any clumps. Make sure to use cake flour as it gives these cupcakes their light and soft crumb. Substituting all-purpose flour could lead to a dense cupcake. Next, measure out the milk along with the sour cream. These two ingredients will help add moisture and will also help create a tender, fluffy cupcake. Alternate adding the dry ingredients along with the wet ingredients. Mix just until the batter comes together, be careful not to over do it! Over mixing can ruin the texture of the cake and cause issues when they bake.

Next you’ll need to grab some bowls to divide the batter in. I used six colors (red, orange, yellow, green, blue, purple) but feel free to use as many as you want. Layer each of the colors one at a time until all of the batter has been used. My liners were filled ⅔ of the way full. You’ll be surprised by how much they will rise in the oven, so don’t worry if they look a little empty- I promise this recipe makes 12 standard size cupcakes! Allow them to bake until the edges become lightly brown, remove and allow to cool. Now onto the frosting!Rainbow Cupcakes with Vanilla ButtercreamPlace your room temperature butter into the bowl of a stand mixer (or a large mixing bowl), add a pinch of salt and vanilla and then beat until the butter becomes smooth and creamy. Carefully add the powdered sugar and then the heavy cream. They key to really yummy frosting is beating it for 2 minutes after everything has been added so that it becomes really fluffy! Trust me, you’ll be kicking yourself for not doing this sooner! Pipe the frosting (or slather it) onto the cooled cupcakes and top with fun sprinkles. Share with 8 year old girls and they’ll love you forever. Seriously though, they thought these were the coolest cupcakes ever! And who could blame them? These are fun, vibrant and perfect for any occasion!

5.0 from 1 reviews
Rainbow Cupcakes with Vanilla Buttercream
Prep time
Cook time
Total time
These fun and vibrant rainbow cupcakes with vanilla buttercream are sure to brighten up any day! Easy to make and perfect for St. Patrick's Day!
Yield: 12
  • ½ c. all-purpose flour
  • 1 c. cake flour
  • 1 c. sugar
  • ½ c. (1 stick) butter, room temperature
  • 2 eggs
  • ¼ c. milk
  • ¼ c. sour cream
  • 1½ tsp. baking powder
  • ¼ tsp. salt
  • 1 tsp. vanilla extract
  • Food coloring

  • Vanilla Buttercream:
  • 2 c. powdered sugar
  • ½ c. (1 stick) butter, room temperature
  • 2 tbsp. heavy cream
  • pinch of salt
  • 1 tsp. vanilla extract
  1. Preheat oven to 350 degrees. Line one standard size muffin tin with cupcake liners, set aside.
  2. In the bowl of a stand mixer, cream butter and sugar until light and fluffy, about 2 minutes. Add vanilla, then eggs one at a time until incorporated.
  3. In a small mixing bowl whisk together flours, baking powder and salt. With mixing speed on low alternate adding dry ingredients and wet ingredients (milk and sour cream). Mix until no flour pockets remain.
  4. Remove bowl from stand and evenly divide the batter between six bowls. Color each bowl as desired (I used six colors: red, orange, yellow, green, blue, purple) and then place a layer of each into every cupcake liner. The batter should fill each about ⅔ of the way full.
  5. Place in oven and bake for 18-22 minutes or until the edges become lightly golden in color and the tops spring back. Be careful not to over bake! They will look slightly moist in the center. Remove from oven and allow to cool in pan for 3 minutes before transferring to a wire rack to cool completely.
  6. While cupcakes are cooling, to prepare the vanilla buttercream, in the bowl of a stand mixer fitted with the whisk attachment, beat butter until smooth, about 1 minute. With mixing speed on low, add vanilla, salt and powdered sugar. The mixture will look clumpy, that's ok. Add the heavy cream and gradually increase mixing speed to high. Beat for 2-3 minutes or until the frosting is light and fluffy. Remove and pipe (or spread) onto cooled cupcakes. Top with desired sprinkles.
-A standard box cake mix can be used in place of the vanilla cupcake recipe. It will make 24 cupcakes which means you will need to double the buttercream recipe.
-I used six colors but you can use as many as you'd like. Just divide the batter evenly between however many bowls (colors) you want.

Recipe Source: adapted from Back in the Day Bakery, Old Fashioned Cupcakes