Rainbow Unicorn Birthday Cake – A Decorating Tutorial

Here is a rainbow unicorn birthday cake I designed recently. The cake was decorated entirely in fondant and has big twinkly eyes and rainbow-colored mane. Since it was a 2 tier cake, having the 2 large eyes sort of like filled up the front of the cake nicely. 

The mane, on the other hand, was made using lots of simple fondant flowers in the colors of the rainbow. Each color came in 3 different sizes. Though it looks like a lot of work with the flowers, they were in fact quite easy and fun to make. 

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How to Make a Unicorn Birthday Cake

Main supplies for the birthday cake:

• Cake – This was a 2 tier cake with the top tier measuring 6 inches and the bottom tier measuring 9 inches. Each tier measured 6 inches in height. The cake itself was made in 2 flavors – top tier was a marble cake (click here for the recipe) and the bottom tier was orange cake (click here for my orange cake recipe).
• Buttercream – Each tier consisted of 3 layers of cake and the tiers were filled with buttercream. I also used buttercream to crumb coat the cakes before covering them with fondant.
• Fondant – I used Satin Ice in white to cover the cakes. I also used Satin Ice to make the unicorn horn, floral mane, the eyes, and the upright alphabets.
• Edible gold paint – I used the gold paint for the unicorn’s horn and ears as well as to paint the birthday girl’s name.
• Shortening – Shortening was used to attached the unicorn eyes to the cake as well as to attach the flowers.
• Purple satin ribbon – This ribbon was used to not only cover the sides of the cake board, it was also used as borders for each of the 2 birthday cake tiers.
• Fondant glue – I used this glue to attach the upright alphabets on the cake.
• CMC powder
• Food coloring – Americolor and Wilton

Assembling the cake:

• Before I started assembling the rainbow unicorn birthday cake, I prepared the unicorn horn and the flowers first. Since both required time to set, I made them 2 days in advance. I have 2 separate tutorials on how to make the horn and the flowers, you can check the details out there.

• Next were the cakes. Once baked, I leveled and layered them with buttercream and covered each tier separately in fondant. I then stacked them on top of each other with the support of bubble tea straws. I also covered the cake board with fondant. 

• The first decoration that went on the rainbow unicorn birthday cake was the unicorn eyes. I drew the eyes on a parchment paper and cut them out of fondant. Click here to learn how I created and attached the unicorn eyes to the birthday cake. 

• I also wrapped the cake board and each tier with purple satin ribbon. Next was the horn. I positioned it on the top tier.

The cascading rainbow mane

• And then, I marked the line for the unicorn’s rainbow colored mane using tiny pinches of fondant:

• Once I was able to visualize the position of the mane using the tiny fondant pinches, I replaced them with a long strip of fondant that started from the unicorn horn at top of the cake, flowing down the back and side and ending towards the bottom front of the cake.

• This fondant strip was to guide the placement of rainbow-colored fondant flowers as well as to provide a slight bump so that the flowers do not appear too flat on the cake especially on the top of the cake.

• And then I arranged the flowers on the birthday cake. I started with larger flowers first. Red flowers went first. 

• Followed by the orange and yellow.

• Next were the green, blue and pink flowers:

• And the final color in the order was purple. This was in the order of rainbow colors too.

• And I continued with the placement of  the flowers, but this time is the reverse order of the rainbow colors, starting with pink, followed by blue, green, yellow, orange, and red:

The unicorn ears

• Once I had the flowers in order, I made the ears for the unicorn birthday cake. I rolled a piece of white fondant with considerable thickness as shown:

• I drew the ear template on a piece of paper and cut out two pieces of fondant for the 2 ears:

• For the inner part of the unicorn ears, I trimmed the earlier ear paper template and marked the shape on each ear using my needle tool. 

• I then curved the base of the ears and set them in a upright position to set. Using the same edible gold dust and lemon extract mixture as the horn, I painted the ears as shown:

• To place the ears on the unicorn birthday cake, I had to make slight adjustments to the flowers on the top tier by removing one of the orange flowers.

• And then, I attached the ears with fondant glue.

• The next step was to fill the gaps in unicorn mane with the medium and small flowers. I also placed a few red flowers on the front of the unicorn horn as shown:

• This was how the back and side of the rainbow unicorn birthday cake looked like with all the flowers on the cake:

The birthday girl’s name in fondant

• Once I have put all the flowers, I went on with the wordings for the birthday cake. I placed the birthday girl’s name in upright font on the cake board. To make the upright standing alphabets, I rolled some fondant (mixed with a little CMC powder) to a thickness of about ¾ cm and cut the letters out using the cutters below:

• I then painted just the surface of the letters with gold paint.

• I let the paint dry and then attached the letters to the cake with fondant glue so that they stay in place securely:

• And this was how the completed rainbow unicorn birthday cake looked like:

Rainbow unicorn birthday cake on a cake stand

Here was how the rainbow unicorn birthday cake looked like sideways:

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And that was how I made my unicorn birthday cake. Hope you enjoyed this tutorial.

Here are my other posts you might want to check out:

• Fondant Unicorn Horn Tutorial
• How to Make Fondant Unicorn Eyes for Cakes
• Fondant Rainbow Tutorial
• Rainbow Fondant Letters Tutorial
• Rainbow Birthday Cake – A Decorating Tutorial

Happy decorating 🙂