Preheat oven to 350 F and spray three 9" round cake pans with Pam baking spray.
Using a hand mixer and large bowl, beat all cake ingredients until combined and smooth.
Divide the cake batter into 3 bowls.
Mix in 2-3 drops of yellow food coloring into one bowl and mix to get a pale yellow color.
Mix in 2-3 drops of pink food coloring into the second bowl and mix to get a pale pink color.
Mix in 2-3 drops of orange food coloring into the third bowl and mix to get a pale orange color.
Pour each batter into their own cake pan.
Place into the oven and bake for 28-32 minutes or until a toothpick comes out clean.
Allow to cool completely.
Frosting
Using a standing mixer, beat all ingredients except for the colors until combined and smooth but stiff with peaks.
Scoop 1 cup of frosting into each of the 4 medium bowls. (There should be frosting left in the stand mixer bowl.)
Mix in a few drops of pink gel food coloring into one of the bowls with the 1 cup of frosting and scoop into a piping bag with star tip.
Mix in a few drops of yellow gel food coloring into the second bowl with the 1 cup of frosting and scoop into a piping bag with star tip.
Mix in a few drops of orange gel food coloring into the third bowl with the 1 cup of frosting and scoop into a piping bag with star tip.
Mix in a few drops of green gel food coloring into the fourth bowl with the 1 cup of frosting and scoop into a piping bag with the leaf tip.
Scoop ½ cup of white frosting into the last piping bag with a star tip.
Building the Cake
Place one cake layer onto the cake board and cut the dome off the cake to make an even layer.
Repeat step with other two layers.
Scoop 1 cup of white frosting onto the bottom layer and spread evenly.
Place the second cake layer on top and spread evenly 1 more cup of frosting.
Place the last layer of cake on top.
Use the remaining white frosting and frost entire cake.
Using the white, pink, yellow and orange piping bag, start piping the “hair” for the unicorn on the top and around one side of the cake to create a “mane.”
Place the horn, ears and eyes from the decorating kit onto the cake.
Using the green piping bag, randomly pipe petals into the hair and mane. Place the icing transfers randomly into the hair.
Place into the fridge to harden the frosting before enjoying!