Birthdays are always that one occasion when we let ourselves set free and enjoy every moment of that day. It’s only once a year after all. And when we have kids, the birthdays become the most critical talk of the town for that month. For her fourth birthday, my elder daughter wanted a unicorn-themed birthday party. And the birthday cake is the star of the show, had to be simply exquisite. I fulfilled my little angel’s wish and made her a Rainbow Unicorn Cake for her upcoming birthday, which she absolutely loved!
Unicorn and rainbow cakes are trending a lot these days. You can find many different themes within the unicorn cake itself. Ours is a rainbow unicorn cake, where the unicorn is wearing an Indian-style headpiece, which is typical of Indian jewelry. You can say it’s an Indian Princess Unicorn who is colorful and cheerful, just like my little girl. There is something really fascinating about unicorns. These are interesting looking magical creatures that have taken over the kids’ fantasy world.
Best sources to make your Rainbow Unicorn Cake
One can find unicorn-themed clothing, accessories, toys, books, school stationery, cartoons, and whatnot. So finding Unicorn-themed birthday supplies was not hard at all. You can find them almost everywhere now. My favorite online place to shop for birthday supplies is Amazon. Off-line, bulk barn is my go-to place for getting some of the best ingredients for cake making. Also, homesense, williams sonoma and michael’s carry amazing baking tools along with many other good quality cake making essentials. I always make sure to check out these places for unique cake ingredients.
However, if you are someone living outside Canada, amazon will be your best bet. You can easily find everything in one place. Though brands and prices may vary as per the demand in your region. When I was living in India, and before amazon came there, I had to hunt a lot for good quality cake ingredients in INA Market in Delhi. However, I did find a few retailers, who dealt with Wilton’s cake products (my preferred brand for making the cake). But even then I didn’t find specific stuff. Now I am not very familiar with the cake market in India, but I am sure Amazon is a great place to start with.
Without further adieu, let’s make the cake I made on our special day. Check out my other Moana theme birthday cake recipe here. Moana is a famous Disney character and this cake is even more special because it’s a healthy cake with some good looks too. Make sure you see it for your next birthday party cake inspiration. Happy Baking!

Ingredients
- 3 boxes Betty Crocker Supermoist White Cakemix
- 7 different Edible Food Colors/Gel colors
- Egg Whites, As per recipe on Cakemix box
- Vegetable Oil, As per recipe on Cakemix box
- Approximately 500-700 gm White Chocolate Chips (sweetened)
- 1-litre Heavy Cream
- About 1 kg Buttercream
- Edible Decorations, As per your choice and need
Instructions
CAKE BASE:
- Follow the recipe on the cake mix package, then divide the dough into seven equal portions. Try to be accurate because baking time will vary if the amount of batter in each baking tray varies. Also, it's better if the height of each cake sponge is the same for an even look. To achieve this, measure the dough you put in first cake tin, and then try pouring the same amount in the rest.
- Add seven colors of the rainbow to your seven portions of batter – one color per share. Remember to mix the batter very well with the colors. Then bake the sponge cakes, following the instructions on the cake mix.
- You can prepare the sponge cakes one day in advance. It is advisable to do so since it'll take you longer to bake all seven of them. Especially if your oven isn't too big, and you do not have seven identical cake tins. When the sponge cakes are completely cold, assemble the cake layers with icing. That's always necessary if you work with the buttercream or chocolate ganache.
CHOCOLATE GANACHE:
- Add heavy cream to a small saucepan and heat on low heat until the cream warms up.
- Add chocolate chips to a large glass or nonreactive bowl. Pour the warmed cream over the chocolate chips. Allow to stand for about 3-5 minutes to soften the chocolate chips altogether.
Stir briskly to combine and until smooth. - Once cooled, use an electric mixer or a wire whisk, whip ganache to incorporate air. This will increase the volume of the ganache.
- Divide ganache equally into 4-5 different bowls. Now add different food colors to each bowl and mix thoroughly.
Transfer the colored ganache to 4-5 piping bags with desirable patterned tips and place them in the fridge overnight to set.
I used color swirl 3-color coupler cupcake decorating set and 4-piece specialty icing tip set.
ACCESSORIES AND ADDITIONS:
- I made one additional sponge cake (light pink colored) and cut out the triangular unicorn ears out of it. It's way faster and easier than working with the fondant, and it looks great too if you add some golden dusting.
- For the single horn of our unicorn, I painted a long ice cream cone gold with edible golden paint – use spray to ease your work.
Other decorations: edible butterflies, edible flowers, golden and silver edible pearls – you can use additions of your choice or stick to flowers made of frosting and ganache.
BUTTERCREAM: I used freshly prepared store-bought buttercream (bulk barn), but you can also make one at home from scratch. I recommend this recipe: https://sallysbakingaddiction.com/2017/05/14/vanilla-buttercream/.
ASSEMBLING THE CAKE:
- Make sure that all the parts of the cake are cold.
- You should remember to keep your working space as cool as possible (crank the AC up!) – the work will keep you warm, I promise.
- Make sure to place the cake on the cake platter that you're planning to use while serving it. It will not be possible to move it once it's assembled. It'd be a pity to lose it after so much work.
- Place the first sponge cake and cover it evenly with a thin layer of buttercream. Place another sponge cake on the top. Do not worry if it's not ideally straight – you can even out the surface with the buttercream in further steps. Also, it is ok, if the buttercream comes out on the sides. You can even out later when icing the sides.
- Repeat the above step until you use up all the cake layers. Make sure to have more buttercream for further steps.
- Now, it's time for the "crumb layer." Put a skinny layer of the buttercream all over the cake – just enough to trap all the crumbs underneath. This layer does not have to be perfectly smooth. Its basically to get rid of all the cake crumbs, so they're not appearing around the "face" of Unicorn later.
- Cover the sides of the cake with a generous layer of buttercream. Also, it is easier to work on this step when the cake is cold. This step is significant because the layer that you're working on right now will become "a face" of your Unicorn soon enough. So try to be as smooth as you can.
CAKE DECORATION:
- With the help of toothpicks, insert cake cut-outs of Unicorn's ears side by side on the top layer of the cake. Leave enough space in between for ganache decoration and a single horn.
- Line all the piping bags of colored and set chocolate ganache. Start with the top layer of the cake. Make swirls or rosettes or any desired patterns.
- Place the cake in the freezer for at least 15 minutes to let the ganache patterns set. Once set, take the cake out and start working on one side of the cake.
- Place edible decorations after the completion of the frosting part. Using tweezers, I made a head string of edible pearls on the top edge of the cake.
- Now using liquid black sugar icing or black candy melts, make the eyes of Unicorn in the central part of the cake keeping eyelashes in upward direction. I made the eyes closed, but you can keep them open. Up to you!
- Put the cake in the fridge until needed for the cake cutting ceremony. Also, insert the horn right before display to keep the height of the cake low as per your fridge space.
Notes
- I used a ready-made cake mix to speed things up. But if you want you can make the sponges from scratch too.
- An important thing to remember is that while baking the cakes, you should use only egg whites. That will ensure that the colors of the cake will come out better, with no weird surprises.
- Note that during your work with the cake, you might need to put it back to the fridge if buttercream/chocolate ganache gets too runny. Also, make sure to keep enough free space to your fridge/ freezer to put the whole cake in – it is going to be rather tall.
- Working with ganache on the sides will be a bit challenging. So you can choose to use buttercream frosting here. Just add desired colors to the buttercream and transfer it into the piping bags.