1 box yellow cake mix
1 vanilla instant pudding mix
1 cup water
7 gel food coloring gels(red, orange, yellow, green, blue, indigo, violet)
1 cup white candy melts
Preheat oven to 400 degrees F. Prepare a 9 by 13 baking pan with parchment and non-stick cooking spray. Mix both mixes, eggs, water, and oil in a large bowl. Divide batter equally into 7 small bowls and stir in food gels. Pour red batter first and bake for 3-4 minutes. Continue with pouring one color at a time and baking for 3-4 minutes each layer, the last layer bake for 5 minutes. Cool on resting rack. Melt white candy melts in a microwave (30-second intervals until smooth), coat the top of your cake with it.
Once it hardens cut into rainbows and enjoy!