Rainbow Swirl Cake

This truly easy-to-make one-pan rainbow swirl cake is topped with vibrantly colored fondant polka dots for a fun cake anyone can make! No matter where you take this cake, it is always a crowd-pleasing favorite with its bright colors and fantastic flavors!

See my Rainbow Lollipop Drip Cake and my other Rainbow Layer Cake.

Of course, this is a wildly popular kids' birthday cake, but it can go anywhere from office parties to anything you can think of! The bright, beautiful cake will surely be the party's hit!!

What I love most about this method for rainbow cakes is that it is so easy to make these colorful layers! It's one of the best and easiest ways to make a rainbow cake, whether you are doing a single-layer cake or even more layers than I used here!

This fun and festive dessert is always the talk of the party! For more delicious cakes, check out all of my fabulous cake recipes!

Jump to:

• 🥘 Ingredients
• 🔪 How To Make A Rainbow Swirl Cake
• 💭 Tips & Notes
• 🍰 More Amazing Cake Recipes!
• 📖 Recipe Card
• 💬 Reviews

🥘 Ingredients

All you need for this one-pan rainbow swirl cake is a few standard baking ingredients. Of course, you could buy buttercream frosting or fondant, but my recipes are super easy and delicious!

• All-Purpose Flour - 2 ¼ cups of flour.
• Sugar - 1 ⅓ cups of granulated sugar.
• Baking Powder - 3 teaspoons of baking powder (not baking soda)!
• Salt - ½ teaspoon of salt.
• Milk - 1 cup of milk at room temperature.
• Butter - ½ cup of butter that has been melted and cooled.
• Eggs - 2 large eggs at room temperature.
• Vanilla Extract - 1 teaspoon of vanilla extract.
• Almond Extract - ½ a teaspoon of almond extract, or omit it and use 2 teaspoons vanilla extract.
• Gel Food Coloring - In your desired colors.
• Vanilla Buttercream Frosting - 1 batch of my buttercream frosting recipe.
• Marshmallow Fondant - 1 batch of my recipe or 1 batch of my fondant without marshmallows.

*Be sure to see the recipe card below for ingredients, amounts & instructions!*

🔪 How To Make A Rainbow Swirl Cake

This one-pan method for making a brightly colored rainbow cake is super easy to bake and just as easy to assemble and decorate!

My cake is topped off with a buttercream frosting crumb coat, then a layer of marshmallow fondant before we add more rainbow-colored fondant polka dots!

Mix, Color & Bake The Cake

1. Prep. Preheat your oven to 350°F (175°C) and lightly coat 2 8-inch round cake pans with butter or non-stick baking spray.
2. Mix dry ingredients. In a large mixing bowl or the bowl of your stand mixer, add all of the dry cake ingredients (2 ¼ cups all-purpose flour, 1 ⅓ cups sugar, 3 teaspoons baking powder, and ½ teaspoon salt) and mix them together.
3. Add wet ingredients. Add your wet ingredients (1 cup milk, ,½ cup butter, 2 large eggs,1 teaspoon vanilla extract, and ½ teaspoon almond extract) to the dry ingredients and mix on medium speed for about 2 minutes, or until smooth. Make sure to scrape the sides and bottom of the mixing bowl.
4. Color the batter. Once the cake batter is mixed well, divide it into 6 equal portions. (You can use more or fewer colors or opt for whatever colors you like.) Color each portion of batter a different color with gel food coloring, mixing until the color and batter are thoroughly combined.
5. Make swirl layers. In your prepared 8-inch cake pans, layer the colors by adding a spoonful of each color into the center. The colors will spread and push out to form the rainbow layers on their own. Repeat until you have used all of the cake batter.
6. Bake. Bake your cake centered on your oven's middle rack for 30-35 minutes or until an inserted toothpick, knife, or cake tester comes out clean. Remove from the oven and allow the cake to cool slightly, about 5 minutes.
7. Cool. Transfer the baked rainbow cakes to a wire cooling rack so they may cool completely before you decorate.

Assembling the Rainbow Cake

1. Color your fondant. After mixing 1 recipe of buttercream frosting and making 1 recipe of marshmallow fondant, split the fondant batch to add colors. Wrap the fondant tightly and securely until (and between) ready to use.
2. Level the cake rounds. Level each of the cake rounds then spread a small amount of buttercream beneath where the center of the cake will sit to hold it in place. Put the first cake layer on top of your serving plate or a turntable.
3. Pipe buttercream. Pipe buttercream frosting around the outside edge of your cake. Then, either continue to add buttercream to make an even layer in the center of your cake or fill it with a flavored filling of your choice.
4. Add a second layer. Set your second cake round on top of the first and even it out until it is securely in place. Frost the sides and top in a thin ¼-inch layer. Place the cake in the fridge before covering it with fondant.
5. Add fondant. Roll your fondant out into a single round large enough to cover the 8-inch cake (16 inches wide and ¼ inch thick). Drape the fondant over the cake and smooth it toward the base.
6. Add polka dots. Using water, apply your cut polka dots to the fondant covering the cake. Allow them to dry while you apply any other desired trim or decorations.
7. Store or serve. Once done, store your fondant-covered cake at room temperature so long as you do not use fruit or dairy fillings that can spoil.

This delightfully fun polka dot swirl cake is wonderful for birthday parties or any celebration!

Everyone will be so impressed that this beautiful cake was made by hand and not purchased at the bakery. Enjoy!

💭 Tips & Notes

• Using Clear Vanilla Extract: For a vibrant color in your cake, consider using clear vanilla extract. This can be found in the party and cake supplies sections at stores like Walmart, Hobby Lobby, or Michael's Crafts.
• Gel Food Coloring: Gel food coloring is recommended over liquid for ease of use, especially when coloring cake batter, icing, or frosting. Gel food coloring is available at the same locations as clear vanilla extract.
• Chilling the Cake: For easier decoration, chill your cake before starting. Wrap the individual cake layers in cling film and refrigerate them before applying the crumb coat. This makes the decorating process smoother.
• Storing the Cake: A fondant-covered cake can be stored at room temperature in a container for up to 3 days or refrigerated for up to a week, depending on the fillings and toppings used.
• Freezing the Cake: For long-term storage, wrap the cake tightly in plastic wrap, then in foil, and freeze it for up to a year. The suitability for freezing depends on any perishable toppings or fillings. To serve, thaw the cake in the fridge overnight and then let it come to room temperature before slicing and serving.

>>>>See all of my recipes here<<<<

🍰 More Amazing Cake Recipes!

• Maraschino Cherry Coffee Cake
• Mandarin Orange Cake
• Jamaican Black Cake
• Cherry Chocolate Dump Cake
• Pineapple Sunshine Cake
• Chocolate Fudge Cake with Fudge Frosting

📖 Recipe Card