5 from 1 vote
a colorful unicorn themed birthday cake
Unicorn Birthday Cake

This recipe provides instructions about how to make and decorate a unicorn-themed birthday cake. The focus is on the decoration and uses a box cake mix and store bought frosting rather than bake from scratch.

Course: Dessert
Cuisine: American
Keyword: birthday cake, unicorn
Servings: 8 people
Author: Michelle Barsness
Shopping and supply list
  • 1 vanilla cake mix (ie, Betty Crocker vanilla cake)
  • 3 tubs vanilla buttercream frosting (ie. Betty Crocker vanilla frosting)
  • 1/4 cup confectioner's sugar
  • gel food coloring black, plus 3 other colors of your choice
  • 1 box of fondant
  • 1 sugar ice cream cone
  • cake decorating sprinkles (ie, multi-color, pink)
  • 2 8 inch non-stick round cake pans
  • parchment paper
  • non-stick baking spray (ie, PAM)
  • Any ingredients on the back of the birthday cake mix box (ie, water, eggs, oil)
  • 1 cake leveler or large serrated knife
  • 1 cake decorating spatula
  • 4 cake decorating piping bags or zip-lock bags 1 large, 2 medium, 1 small
  • 4 cake decorating tips 1 round tip (size #2 or #3) 3 other various sized star or flower tips, your choice
  • 1 small clean paint brush
  • 1 cake decorator turn table or cake stand (optional)
Bake two cakes
  1. Use 8 inch round non-stick cake pans. Place a cake pan on top of a sheet of parchment paper. Trace around the outside of the pan with a pencil. Do this 2 times. Cut out the circles. Place the parchment paper circles inside of the cake pans. Spray each pan liberally with baking spray. Pre-heat the oven. Follow the instructions on the back of the cake mix box to prepare the cake batter. You will have better results if the eggs, water, oil are at room temperature. Evenly divide the cake batter in-between the cake pans. You can do this either by weight using a kitchen scale or fill each pan about 3/4 way full. Bake the cake for length of time and temperature specified on the cake mix box (typically 25 - 30 minutes). Use a toothpick or cake tester inserted in the middle of the cake. It should come out clean when done. Allow the cakes to cool completely before removing them from the pans. Level the tops of each cake using a Wilton cake leveler or a large serrated knife.

Build and frost the cake
  1. Use a cake stand or cake decorating turn-table to build the cake layers. Start with a thin all-over crumb-layer of frosting. Gently spread the frosting using the cake decorating spatula. Add frosting on top of the base layer (or use another filling such as pudding, compote etc.) Place the second cake on top and continue with the all-over crumb layer of frosting. Chill the cake in the fridge for 15 minutes before frosting again all over. You will use about one tub of frosting. Use the remaining tubs frosting for the mane and eyes decoration. Chill the cake while you prepare the decorations.

Unicorn horn
  1. Use a sugar ice cream cone for the unicorn horn. Use parchment paper and your fingers to roll out the fondant. Similar to play-doe fondant will roll out and cut into any shape. You can wrap the base of the horn with a small worm-like length of fondant. Create another long (about twice the size of the cone) worm-like piece of fondant (medium-sized width). Start at the top of the ice cream cone. Work your way down wrapping the cone with the fondant strip. This creates the swirly horn effect. Use your fingers or fondant shaping tool to gently press and flatten the fondant how you like into the cone.

  2. If you'd like to decorate the horn with sprinkles add a little water (1 tbsp) to 1/4 cup of confectioner's sugar. Create a slurry or royal icing. Use a small paint brush to brush on the icing in desired areas. Hold the horn with one hand while adding the cake decorating sprinkles and turn the horn. Work quickly. This should help adhere the sprinkles. Be creative. On my unicorn horn we used multi-colored cake sprinkles near the base and pink cake sprinkles in the middle. The top of the horn was left white fondant.

Unicorn ears
  1. Use a rolling pin and parchment paper. Roll out a thin layer of fondant (about 1/4 inch). Free-hand cut out two large tear-drop shapes for ears. You can paint the inside of the ears by mixing a tiny amount of pink gel food coloring in 2 tbsp of water. Use a clean small paint brush to paint it. Leave about 1/2 an inch all the way around the outside of the ear white. The ears are quite delicate. We used a couple small tooth picks inserted at the base to help prop them up on the cake.

Unicorn mane
  1. Frosting should be at room temperature. Place the horn in the center of the cake. Add the ears, one on each side. Reserve and set aside about 3 tbsp frosting for the eyes. Divide the remaining frosting into three bowls. Use about 1 1/2 cups frosting for the predominate color. In our unicorn cake this color was pink. Divide the remaining frosting in two. Add a small amount of gel food coloring to each bowl. Add a little color at a time and mix well until you reach the desired colors you want. In our unicorn cake we chose purple and turquoise. Transfer each color into a separate piping bag fitted with a different decorating tip. Use a large star tip for the most predominant color and two smaller star tips for the other two colors. You can also use zip-lock bags if you do not have multiple decorator piping bags.

  2. Start with the most predominant color. Apply one large swirl in the center.  In this case pink. Alternate frosting colors and swirl techniques around the first one. Continue your way along the side and back of the cake until you are happy with it. Use a mix of large swirls and small ones. There is no right or wrong way. Practice the frosting techniques on parchment paper first if necessary.

Unicorn eyes
  1. Add black gel food coloring to the reserved 3 tbsp of frosting. Practice eyes on parchment paper before applying to the cake. Or make the eyes on paper, pop them into the freezer to chill and set. Then transfer them onto the cake with a knife. Use a small round tip (#2 or #3 size). Create upside down "U" shape and add two one inch lines on either side for lashes.

    a colorful unicorn themed birthday cake
  2. Store the cake in the fridge. Remove the cake and bring to room temperature at least a couple hours before serving.

Recipe Notes

Additional tips:

Did you make a unicorn-themed birthday cake? I'd love to hear about your experience. Visit https://pineneedlesinmysalad.com/unicorn-birthday-cake to leave a comment. Share a photo of your cake in Instagram and tag me @pineneedlesinmysalad