Amelia’s 5th Rainbow Unicorn Birthday Cake

It’s Amelia’s 5th birthday! Every year, I say I can’t believe it but I seriously can’t believe it’s been 5 years. My baby! My first born is 5!img_8963

She loves birthday’s almost as much as me, too, especially hers! 🙂 From the balloons, to the presents and of course the cakes, she loves them! And I can’t say I blame her!

So for every birthday, I challenge myself to make a new cake I haven’t done before. Something hard but that she’ll love. Last year, it was a slightly simpler, but still fun cake because we had just moved into our house and this was the only baking pan I could find. 🙂

This year, she asked for another rainbow unicorn cake. If you remember, I made one of these for her 3rd birthday. But since it’s Covid times and she’s not having a party :(, I wanted to make her a different unicorn cake (albeit smaller) but still amazing.

So here we are. A 5th rainbow unicorn birthday cake – it’s super fun, made from just one 9×13 sheet pan cake and super delicious. If you have a unicorn loving child, this is a super fun cake to make!img_8966_jpg

Happy cake decorating!

Amelia's 5th Rainbow Unicorn Birthday Cake

  • Servings: 10-12 slices
  • Difficulty: hard
  • Print



  1. Preheat oven to 350 degrees. Line a 9-inch by 13-inch cake pan with parchment paper and spray the paper with cooking spray.
  2. Make the cake: divide white cake batter into 6 bowls (about 3/4 cup in each). Color one bowl red, another orange, yellow, green, blue and purple. Splatter (with a spoon) or pipe alternating colors into cake pan until all colors are incorporated. Tap the pan on the counter a few times to level the cake batter and to remove any air bubbles. Bake according to instructions on the cake mix box (mine took about 33 minutes). Remove cake and allow to cool completely.
  3. Assemble the cake: once cooled, invert cake onto a cutting board. Cut cake in half so you have two 9 by 6 1/2-inch pieces – one piece will be the unicorn’s body. Cut the other piece in half so you have two 6 1/2 by 4 1/2-inch pieces – one piece will be the unicorn’s head. Cut two 2 by 3-inch pieces for the unicorn’s legs. Trim as needed and discard or eat the remaining pieces. Assemble the cake by placing the 9-inch by 6 1/2-inch cake in the lower half of your cake board forming the unicorn’s body. Set the 6 1/2-inch by 4 1/2-inch piece about 2 1/2 inches from the top edge of the larger cake forming the unicorn’s head. Place the two leg pieces under the body piece about 3/4 of an inch from either edge.
  4. Decorate the cake: spoon 3/4 frosting into pastry bags or ziploc bags fitted with #21 star tips. Pipe white stars over the large cake. Pipe stars over 3/4’s of the head and legs, leaving room to pipe on pink hooves and a pink snout. Fill in hooves and snout with remaining 1/4 pink frosting.
  5. Using the black writing gel, draw on the eye, nose and mouth.img_8947
  6. To make the ear: make candy clay (12oz of candy melts melted + 1/4 cup corn syrup – mix together and dye any color – ready in 1 hour). Roll our a 1oz piece of blue candy mold and cut out a teardrop shape. Repeat with a smaller piece of red candy mold and lay the red on top of the blue. Attach to top right corner of the head and let dry (about 10 minutes).
  7. To make the mane and tail: for the mane, cut out 2 pieces of red and 2 pieces of blue and roll them each into a log. Trim the edges and attach to the back of the head under the ear. Repeat with 5 pieces for the tail and attach to the back of the body. (Note: more colors can be used, if desired).
  8. To make the horn: trim a sugar cone down to half it’s size by slowly breaking off pieces. Paint gold luster dust directly on the cone. To attach, cut a small piece of the cake out and insert the cone. Use a small piece of candy mold to hold it level, if needed.
  9. Finish with candles and a big piece of cake! Enjoy! img_8969_jpg

Recipe adapted from and


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