Rainbow Unicorn Cake

READY IN: 2hrs 10mins


  • For the Cake Base
  • 1
    recipe cake of your choice for the cake
  • three 8 by 2-inch round cake pans for the cake
  • For the Cake Decoration
  • 1 12
    recipes of simple vanilla buttercream frosting (recipe follows)
  • recipes of vanilla swiss meringue buttercream frosting (recipe follows)
  • 18
    teaspoon gel green food coloring
  • 18
    teaspoon gel pink food coloring
  • 18
    teaspoon gel sky blue food coloring
  • 6
    inches ball white fondant
  • 2
    inches ball of pink fondant
  • 2
    inches ball of black fondant
  • For Simple Vanilla Buttercream Frosting
  • 2
    cups unsalted butter, room temperature
  • 4
    cups confectioners' sugar, sifted
  • 1 -2
    teaspoon whole milk, optional. If the buttercream is too stiff, a touch of milk will help loosen it a little
  • For Vanilla Swiss Meringue Buttercream Frosting
  • 1
    cup egg white (about 7 to 8 large eggs)
  • 2 14
  • seeds of 1 vanilla bean (optional)


  • Tools:
  • 1 piping bag fitted with a multi-opening tip.
  • 1 piping bag fitted with a small leaf tip.
  • 2 piping bags each fitted with open star tips.
  • Wooden skewer cut into 2 equal pieces plus additional wooden skewer (cut to fit, if need be).
  • To make the simple vanilla buttercream:
  • In the bowl of a stand mixer with a paddle attachment, beat the butter on high speed until it is light and fluffy, about 2 minutes. Scrape down the sides of the bowl with a spatula. Add the sifted confectioners’ sugar, vanilla extract, and milk, if using. Mix on low speed to combine the ingredients. Once the sugar is incorporated, crank the mixer to high speed and beat the mixture for another 2 minutes, until it has more than doubled in volume, for a fluffy whipped frosting.
  • Leftover buttercream can be stored in an airtight container in the fridge for up to 2 weeks or in the freezer for 1 month; bring it back to room temperature and rewhip in a stand mixer before using. This recipe can easily be halved or doubled.
  • To make the vanilla swiss meringue buttercream:
  • To ensure that the metal bowl of your stand mixer is completely clean, dry, and free of grease, give it a quick wipe out with a halved lemon, then rinse and dry it thoroughly.
  • In the bowl of the stand mixer fitted with the whisk attachment, mix the egg whites and the sugar on low to combine into a sugary slurry. Fill a medium saucepan with a few inches of water and place it on the stovetop over medium-high heat. Set the mixer bowl on top of the saucepan to create a kind of double boiler, making sure the mixer bowl doesn’t touch the water.
  • Heat the egg and sugar mixture until it reaches 160°F on a thermometer or is hot to the touch, whisking occasionally. This usually takes me about 5 to 7 minutes.
  • Carefully return the metal mixing bowl to the stand mixer, with the whisk attachment in place. Now, bring the mixer up to high speed and beat the mixture for 8 to 10 minutes, until you’ve created medium-stiff peaks and it’s a billowy, sticky, cloudy meringue. Whipping the meringue will also help cool down the bowl.
  • Swap out the whisk for the paddle attachment. Make sure your meringue has cooled sufficiently before adding the butter—the bowl shouldn’t be hot, just slightly warm, if that. With the mixer on low speed, add the butter a few pieces at a time, until all the butter is incorporated—it will look like a thick soup at this point. Add the vanilla extract, if using, the vanilla bean seeds, along with the pinch of salt (and any small amount of gel color if so desired), then bring the speed up to medium-high and beat until a fluffy, silky, magical buttercream has formed, about 2 to 3 minutes.
  • If your Swiss meringue buttercream turns into a soupy disaster, try placing the whole bowl in the fridge for about 5 to 10 minutes to cool it down a bit, then bring it out and try whipping it again, first on low speed, then bringing it up to high speed. Or try adding a few more chunks of butter to the mix.
  • If your Swiss meringue buttercream becomes a gross-looking, curdled mess, try lightly heating the whole bowl over a low-boiling pot of water for 1 minute, just to get some heat back in there. Once it’s warmed up a teensy bit, try mixing it again. You will be amazed at how a bowl of seemingly awful-looking buttercream can actually be saved and whipped back into a gorgeous, fluffy, satiny, creamy frosting.
  • Vanilla Swiss Meringue Buttercream will keep in an airtight container for up to 1 week in the fridge or up to 1 month in the freezer. Bring it back to room temperature and gently rewhip before using.
  • Prepare the cake. Bake the three layers of cake according to the recipe instructions. Level, fill, and frost your cake using the uncolored buttercream.
  • Fill a piping bag fitted with a multi-opening tip with about half of the uncolored buttercream.
  • Pipe the fur. Starting at the bottom edge of the cake, hold the piping bag at a 90-degree angle against the cake and squeeze in short spurts to create a line of frosting dots from bottom to top. Continue piping lines all the way around the cake, nestling the lines closely together. Pipe the top of the cake in the same manner until the entire exterior is covered in fur.
  • Place ½ cup of the remaining buttercream into a medium-sized bowl and tint it green. Fill the leaf-tipped piping bag with this buttercream.
  • Divide the rest of the buttercream evenly between two medium-sized bowls, tinting one pink and the other, blue. Fill one of the star-tipped piping bags with the pink buttercream and the other with the blue.
  • Make the fondant features. Clean and dry your hands completely. First we will make the ears. Pull off two 1½-inch balls of white fondant; shape them into triangles about ½ inch thick. Using a 1-inch ball of pink fondant, form two flat triangles for the inner ears. Adhere these to the white triangles with a tiny amount of water. Insert wooden skewers into the bottoms of the ears and set aside.
  • To make the unicorn horn, pull apart 1½ inches of white fondant and roll it into a thick snake about 4 inches long. Do the same with the remaining pink fondant. Twist the white and pink fondant together, then roll the twist between your hands to compress it. Shape the tip of the horn into a point, then insert the additional skewer through the bottom center of the horn.
  • Reserve two tiny bits of white fondant for the eye highlights. To make the snout, use the remaining white fondant and roll out a half circle 6½ inches wide by 1½ inches high by about ? inch thick. Using a sharp paring knife or pizza roller, trim to shape. With the trimmings, make three little ½-inch-long U shapes; attach to the half circle with a tiny amount of water to make two nostrils and a smile.
  • Divide the black fondant into two equal balls, flattening them gently with your fingers to make ?-inch-thick circles. Use the two bits of reserved white fondant to create two tiny dots. Adhere the dots onto the black eyes using a toothpick and a teensy amount of water.
  • Place the ears and horn on the top of the cake. Place the eyes and snout on the front of the cake. Gently press all the pieces into the buttercream.
  • Using your two piping bags fitted with the open star tips and filled with colored buttercream, begin piping rosettes and drop stars on the unicorn head, alternating colors as you see fit and adding a cascade of swirls and drop stars to the center front, like a tendril of hair. Continue the curls and swirls all the way down the back of the unicorn’s head—create a power mane full of magic! Finish by adding piped leaves using the piping bag fitted with the leaf tip for more texture and color.
  • Tip: For an extra flowery feel, add a few edible flower petals or whole organic flowers, such as roses or carnations. This is also a great time to use any extra buttercream roses you might have stored in your freezer.
  • https://www.amazon.com/Coco-Cake-Land-Pretty-Decorate/dp/1611803152/.