Rainbow Cake
on Jun 09, 2022, Updated Jun 28, 2024
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Who doesn’t love an excuse to make a beautiful, vibrant Rainbow Cake! This cake will make you extra happy because it is surprisingly simple too.
This rainbow cake is a cinch because you use a cake mix! Using a mix makes it quicker to whip up without sacrificing any of the flavor. You are going to love the bright, colorful layers all topped with beautiful white frosting and fun rainbow frosting swirls. So fun!
Have you ever noticed the price to buy a cake from the store or a bakery? It is absolutely insane. This rainbow cake not only looks good and tastes delicious-but it is also inexpensive! Total win in my book. The use of the box cake mix is my secret to make it cost effective and fast to make.
The cool thing about being an adult is that you can have cake ANYTIME! No need to wait for a birthday or special occasion. A rainbow cake would be so fun to bust out on a regular ol’ Tuesday, don’t you think? Rainbow cake would be a great way to celebrate turning another year older, graduation, baby shower or the beginning of summer!
Table of Contents
Why You’ll Love This Recipe
- This cake looks bakery fancy but costs so much less!
- It uses box cake mixes so it’s super easy to mix up.
- It is easy to customize.
Recipe Ingredients
For the cake
- 2 boxed white cake mixes
- water, oil, & eggs (whatever your mixes call for)
- gel food coloring – available at any craft store that sells cake decorating supplies, often under the Wilton brand name
For the frosting
- Unsalted butter – definitely use butter here.
- Cream Cheese
- Powdered Sugar
- Heavy cream – cream makes the texture so creamy and rich but milk will work in a pinch.
- Vanilla – this is a great place to use a fancy vanilla if you have it.
- Salt
See the recipe card below for full information on ingredients and quantities
Popular Substitutions and Variations
- Almond extract is a great substitute for Vanilla extract. It gives more of a wedding cake flavor. It is much stronger than vanilla though so start with a small amount and add a tiny bit more until you have the flavor you want.
- The colors are completely customizable. You could easily use favorite colors or adapt it for a baby or wedding shower.
How to Make a Rainbow Cake
For the cake:
Step #1. Spray the cake pans with non-stick spray or butter and flour them.
Step #3. Stir in red food coloring into the first bowl, orange food coloring into the second bowl, and yellow food coloring into the third bowl. The colors should be very bold.
Step #5. Let the cakes cool in the pan for 5 minutes then transfer to a cooling rack.
Step #7. Make the second cake mix according to package directions, divide it evenly into three bowls, and color one bowl with green food coloring, one with blue food coloring, and one with purple food coloring, again making sure the colors are bold.
Step #9. Level all the cakes using a sharp knife or cake leveler.
Step #2. Make the first cake mix according to the package directions. Divide it equally into three bowls.
Step #4. Pour each color of batter into a separate cake pan and bake according to the package directions until a toothpick comes out clean or the top springs back into place when lightly touched.
Step #6. Once the cake pans have cooled, wipe them out and then repeat step #1.
Step #8. Bake the three pans according to package directions until the cakes test done, then repeat step #5 for these layers.
Step #10. Place all the cake layers in the freezer while you make the frosting.
For the Frosting:
Step #1. Using a stand mixer or a bowl and hand mixer, beat together the butter and cream cheese.
Step #3. Add cream, vanilla, and salt. Beat until smooth and fluffy.
Step #5. Color one bowl for each color: red, orange, yellow, blue, and green. Place each color in a piping bag.
Step #2. Add powdered sugar and beat until it comes together.
Step #4. Remove five 1/2 cup portions of frosting and place each in its own bowl.
Step #6. Place the remaining white frosting into a large piping bag. Assemble the cake as follows in the recipe directions.
Recipe FAQs
I used 2 box mixes for this cake. I bought the white cake mix and you can choose your favorite cake mix brand.
I recommend using gel food coloring. It is highly concentrated so you will only need 1-2 drops. Using gel food coloring offers the most vibrant colors in my opinion. Wilton makes a food color called Color Right that is extra concentrated food color and it does a really nice job.
You sure can! Actually it is best to make a cake ahead of time so that you can put it in the freezer. Working with cake layers that have been frozen will lend to easier frosting. Plus that means that you can make them ahead of time!
In between the rainbow layers I lathered this delicious vanilla buttercream frosting that is very easy to make. This will make each color pop and taste super yummy!
Expert Tips
- Be careful to mix your batter until it is all combined but not more and not less! Too much mixing will make your cake tough and too little will leave clumps of unmixed ingredients.
- If you enjoy making fancy cakes, consider investing in a couple of tools like a turn table and an icing spatula, or even a cake carrier, that will make decorating, storing, and transporting your cake easier.
More Cake Recipes to Consider
From Scratch Recipes
Blueberry Coffee Cake
From Scratch Recipes
Lemon Bundt Cake
Cakes
Blueberry Boy Bait
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Rainbow Cake
Ingredients
For the Cakes
- 2 boxed white cake mixes, (around 15 ounces each)
- water
- oil
- eggs
- gel food coloring
For the Frosting
- 1 ½ cups unsalted butter, at room temperature
- 4 ounces cream cheese, (½ block), at room temperature
- 8 cups powdered sugar, (a 2 pound bag)
- 2-4 tablespoons heavy cream
- 2 teaspoons vanilla
- Pinch of salt
Instructions
To Make the Cakes
- Spray the bottom of 6 inch cake pans with baking spray (I only have 3 pan so I worked in batches, it generally works better for space in the oven too). If you don’t have baking spray, you can butter the pans very well and dust the inside of the pans with flour.
- Make the first box cake mix according to the package directions and divide the batter evenly into 3 bowls.
- Color one bowl red, one yellow, and the last orange. The gel food coloring should have some indication on how much to use, but the batter should be very bold in color.
- Bake according to directions on the box. You’ll know that the cakes are done when they spring back when lightly touched. If you lightly poke them and it leaves an indent in the cake, bake it a few minutes longer.
- Allow the cakes to cool on a wire rack for 5 minutes before removing it carefully from the pan. I like to place a cooling rack on top of my slightly cooled cake and then flip it over with the cooling rack on top (so that the rack is now on the bottom), then remove the pan and allow the cake to continue to cool on the rack.
- Once the pans have cooled, wipe them clean and spray them with baking spray or grease and flour them well.
- Make the second box cake mix and again divide batter into 3 bowls.
- Color one green, one blue, and the last purple. (I decided last minute that I didn’t want to use purple, so I left that layer out and did not add purple to the outside of the cake at all. You can for sure work with 6 layers and purple on the outside too, 5 worked just as well).
- Bake according to directions on the box.
- Allow the cakes to cool on a wire rack for 5 minutes before removing it carefully from the pan. Allow all of the cakes to cool completely.
- Level all the cake layers using a sharp knife or a cake leveler. Mine were all about 1 ½ inches thick. A consistent thickness looks really nice in the finished cake.
- Place cake in the freezer while you make the frosting (since it’s only going to be there 15-20 minutes, I don’t worry about wrapping it in plastic or anything, I just put my cakes on cookie sheets and place the whole thing in the freezer).
To Make the Frosting
- I like to use a stand mixer to make this icing recipe, but you can use an electric hand mixer as well. It’s hard to get it very fluffy and creamy by hand though.
- Add the butter and cream cheese to a large bowl or the bowl of your stand mixer and beat together until smooth.
- Add powdered sugar and beat until the mixture comes together.
- Add heavy cream, vanilla and salt and mix for 2-3 minutes or until the mixture is very light and fluffy.
- Remove 5 – ½ cup portions from basic white frosting and place those ½ cup portions into separate bowls.
- Color each ½ cup portion a different color- red, orange, yellow, green and blue. Once mixed, place in piping bags.
- Fill a large piping bag with the remaining white frosting.
To Assemble the Cakes
- Stack the chilled cakes with a generous portion of white frosting between each layer.
- Cover the cake with a very thin layer of frosting to seal in all the crumbs and use an offset spatula to evenly spread that layer out. It’ll be thin and a little messy, this is called the crumb coat.
- Chill cake in the refrigerator for 15 minutes to 1 hour.
- Pipe a thick white line of frosting along the bottom of the cake
- Pipe a red line of frosting on top of white line.
- Continue adding lines of frosting in orange, yellow, green and blue.
- Pipe white frosting to cover the remainder of the cake
- With a long spatula or bench scraper smooth out the frosting.
- Frost the top of the cake as well and spread it smooth with a long metal spatula.
- To make the multicolored swirls on the top of the cake, spread a piece of plastic wrap on a flat surface, pipe thick lines of all the colored frosting, right next to each other, in the middle of the cling wrap.
- Roll up the plastic wrap up so that the strips of icing are rolled together and twist the ends so it looks like a piece of wrapped hard candy. Cut one twisted end off, then carefully place the cut side down into a large piping bag prepared with a large star tip.
- Pipe rosettes on top of cake along the edge.
- Use sprinkles to create a border on the bottom edge of the cake.
- Your fabulous cake is done. Serve and enjoy!
Notes
- You can use 9 inch cake pans for a larger cake if you’d like. You’ll want to use 3 cake mixed in that case (each mix would be divided into only two colors) and adjust the baking time accordingly. You may also need to increase the amount of frosting, depending on what you use for filling between the layers.
- You’ll know that cakes are done when the spring back lightly when touched. If you press them lightly and it leaves an indent in the cake, they need to bake for a few more minutes.
- Because this is a vanilla cake with vanilla frosting, you could easily change out the filling to another flavor of frosting, jam, nutella, lemon curd, etc.
- Though it may be tempting, do not open the oven door while your cake layers are baking. They may crack or fall if you do!
