Unicorn Party Cake

white cake base (sugar, enriched flour bleached, egg white, soybean oil, palm oil, egg yolk with sodium silicoaluminate, nonfat milk, leavening, dextrose, modified tapioca starch, salt, propylene glycol mono and diesters of fatty acids, sorbitan monostearate, tetrasodium pyrophosphate, xanthan gum, sodium stearoyl lactylate, polysorbate 60, mono and diglycerides, calcium acetate, guar gum, cellulose gum, artificial flavor, soy flour, eggs, oil, water, rainbow sprinkles (sugar, cornstarch, vegetable oil (palm, palm kernel), soy lecithin, confectioners' glaze, natural and artificial flavor, colors, unsalted butter, powdered sugar, milk, vanilla extract