Easy Rainbow Unicorn Cake Recipe

This Easy Rainbow Unicorn Cake is 3 layers of tasty fun and magic. Made with an upgraded boxed cake mix recipe and a whipped cream cheese frosting, this cake is as tasty as it is pretty.

Recipe: $12.58 | Per Serving: $0.79 | Servings: 16

🥘 Ingredients

Ingredient Notes:

Yellow Cake Mix- This will be the base of the cake recipe, making it easier and more simplified. You can use Yellow or white cake mix. We also use cake mix as the base in our Tres Leches Layered Cake, Southern Banana Pudding Cake, and Easter Confetti Cake.

All-Purpose Flour- For added gluten, it gives us a better structure.

Instant Pudding Mix- You will need the dry mix from the pudding box. Do not prepare it beforehand.

Pudding- You will need Vanilla Flavored Cook and Serve Pudding (plus the milk to make it).

Cream Cheese- Adding cream cheese will give us a great flavor, but it also helps the frosting to remain stable enough to pipe decorations with.

For specific ingredients and measurements, please see the recipe card below.

🔪 Instructions for Easy Rainbow Unicorn Cake

Batter Prepping

Step 1: Preheat your oven to 350 degrees F.

Step 2: Cut some parchment paper circles the size of the bottom of your cake pans and then spray the sides and bottom of the cake pans with non-stick cooking spray before placing the parchment paper in and spraying them again. This will keep the parchment paper in place so that it doesn't curl up.

Step 3: Set the pans aside and prepare the batter.

Step 4: In a very large mixing bowl, combine the dry cake mix, flour, sugar, salt, and boxed pudding mix with a whisk (Image 1).

Step 5: In another mixing bowl, blend together the eggs, oil, milk, and vanilla (Image 2).

Step 6: Add in the sour cream. Mix until combined (Images 3&4).

Step 7: Add the wet ingredients to the dry ones (Image 5). Whisk together until well blended and no flour streaks remain (Image 6).

Step 8: Divide the batter between small bowls and add food coloring to each (Image 7). Stir until the desired colors have been achieved (Image 8).

Baking and Leveling

Step 9: Spoon the batter into the cake pans, a little at a time from each color until all pans are filled evenly and no unused batter remains. Use a toothpick to swirl the colors around if desired (Images 9, 10 & 11).

Step 10: Bake in the oven at 350 degrees F for 25-30 minutes or until a toothpick can be inserted and come out clean (Image 12).

Step 11: While the cakes are in the oven prepare the vanilla cook and serve pudding according to package instructions and place plastic wrap over the surface of the cooked pudding as it cools to prevent thick skin from forming.

Step 12: Once the cakes have finished baking allow for them to cool in the pans for 10 minutes before flipping over onto a cooling rack.

Step 13: Cool completely, level tops with a bread knife (Image 13).

Step 14: Prepare frosting per recipe. Chill 2 cups for unicorn hair.

Step 15: Pipe a frosting ring on two layers.

Step 16: Spoon pudding inside circles. Avoid overfilling layers (Image 14).

Stacking and Decorating

Step 17: Stack the three cake layers so that the filling is between two layers and the empty layer is the one on top (Image 15).

For added stability, trim plastic straws slightly shorter than cake height and insert through layers as dowels. Optionally, freeze the cake before frosting for better texture.

Step 18: When the cakes are stacked and sturdy, Pipe some white frosting around the centers and sides of the cake. Make sure to get the top as well.

Step 19: Use a long, flat tool like a cake leveler. Hold it at a 45-degree angle towards cake sides. This will push the frosting into the cake as it smooths it out so it can help to fill in gaps and holes. Go around until the cake is covered in a thin layer. It's perfectly fine for crumbs to be stuck in the frosting. This is called a crumb layer (Image 16).

Step 20: Chill the cake and the frosting at this point before doing a final frosting layer. If your cake is frozen solid, you may be able to get away with adding a thicker frosting layer now that the crumb layer is chilled against the cold cake.

Step 21: Add a thick layer of frosting around the sides and top and level it out until smooth. I say thick but really you want it no more than ¼ inch thick as your only goal is to make the frosting thick enough that the cake isn't poking through the sides. The top doesn't matter and can be left as a crumb layer because you will be covering it in unicorn hair frosting.

Step 22: Place the cake back into the fridge as you prepare the hair colors.

Unicorn Hair

Step 23: Remove the chilled frosting you set aside earlier and mix it with any unused white frosting you have leftover from frosting the cake.

Step 24: Divide the frosting by however many colors you want and add some food coloring to each, mixing until blended.

Step 25: Place each frosting into its own piping bag with a fitted tip. A different tip should be used per color as it helps to make things less confusing and more unique.

Step 26: Arrange the bags of frosting in order of largest tip to smallest tip as this will make it easier to grab and use.

Step 27: Grab the cake from the fridge and set it in front of you. Plan out how you want the hair arranged. Do you want the full top covered or just a strip down the middle? Do you want large bangs or small ones? Etc.

Step 28: Once you've got an idea, go for it! Grab the largest tip and make several circles starting in the front and working your way back. Set down the frosting bag and grab the next tip.

Step 29: Use it to fill in some of the gap areas by making circles that are smaller or make stars by pressing down on the tip and lifting straight up. Continue this process until you get to your last color and use that to fill in any of the small gaps still left.

Step 30: Add sprinkles to the hair if desired.

Step 31: Add the unicorn horn and ears; if you haven't already, add the unicorn eyelashes too. These usually come with unicorn kits but can also be made with melted chocolate too.

Slice, Serve, and Enjoy!