Rainbow Unicorn Cake Recipe (2024)

Making a rainbow unicorn cake isn’t as hard as it looks. While this popular cake can be a lot of work, we’re going to take advantage of some shortcuts to help ourselves out. Use this recipe, tutorial, and tips to make a delicious cake for a special occasion.

Using boxed cake mixes and a unicorn cake topper kit that includes the horn and eyelashes takes away some of the labor-intensive work making this an easy rainbow unicorn cake recipe. These time-savers also eliminate the need to work with fondant or having to place specialty items like edible gold paint in your shopping cart.

Don’t cheat on the buttercream though. There’s nothing like homemade buttercream frosting for both taste and decorating results.

Kids will love both the unicorn theme and the special rainbow surprise after the cake is sliced. You can make a rainbow unicorn birthday cake or enjoy it as a sweet treat anytime!

Rainbow Unicorn Cake Ingredients

2 Boxed White Cake Mixes

Prepared Medium Consistency Vanilla Buttercream Frosting (for decorating)

Prepared Thin Consistency Vanilla Buttercream Frosting (for icing) – See notes on Wilton Vanilla Buttercream recipe above on thinning your medium consistency recipe

Gel food colors

Unicorn Cake Topper Kit

How to Make a Unicorn Cake

Prepare cake mix according to box instructions. Be sure to separate the eggs and use only egg whites so the batter will have strong colors giving you a nice rainbow effect.

Evenly separate the cake mix into four bowls and add electric gel colors. 2-3 drops of different color food coloring per bowl should be enough.

Lightly grease cake pans and pour batter into prepared pans.

Bake cakes according to box instructions checking at the 15-minute mark.

Remove from oven and allow to cool at room temperature until the cakes are cool enough to be wrapped in plastic wrap and placed in the freezer.

Make your buttercream with an electric mixer while the cakes cool in the freezer. I use Wilton’s classic recipe and my stand mixer with whisk attachment to make the best buttercream frosting for all my cakes.

Crumb coat the cake with a thin layer of white frosting making sure to put the buttercream in between each layer as you build a cake. The easiest way to do this is directly on the base of a cake stand or on a disposable cake board.

Once the whole cake is frosted, prepare your colored icing and put it into piping bags with star tips. A medium-stiff consistency icing is going to be required to create the unicorn mane roses on top of the unicorn’s head.

Use different shape/size star tips to create the roses and border as you like. See the photo below. This is where a coupler comes in handy.

Unicorn Rainbow Cake Recipe Notes

• Because these are 1-inch rainbow cake layers they may cook faster than your box tells you. Begin to check them at the 15-minute mark.
• Cakes are done when you stick a toothpick in it and it comes out clean.
• While freezing the cakes is not necessary it is strongly encouraged as it will make the icing of the cake easier when it’s time to assemble.
• If you are in a rush chill the cakes in the fridge for at least two hours before attempting to assemble the cakes or else the cakes can come apart when you are icing them.
• While using a coupler is not necessary for this particular activity it will be helpful to change the tips out.
• A medium-stiff consistency icing is going to be required to create the roses on top of the unicorn’s head.
• Make sure you hold your piping bag at a 45° angle. Apply even pressure when squeezing out the icing. Stop squeezing and then pull the tip away.

Cake Decorating FAQs

📖 Recipe

Enjoy your beautiful rainbow unicorn cake!

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