Baking Rainbow Cake Layers
Your oven should be heated to 350°F. Place the pans on the oven racks with space between them: You want air to circulate around the cakes as they bake, because this will help keep the tops even. Cakes should bake 28 to 30 minutes or until a toothpick inserted in the centers comes out clean. Cool cakes in the pans for 15 minutes to set, then gently remove from the pans and cool on wire racks. It does take a while to completely cool a cake, and you shouldn’t frost a warm cake, so be patient.