Preheat oven to 350
Grease bundt cake pan
Mix the white cake according to box instructions
Separate batter into thirds.
Mix green food coloring in one third. Mix red food coloring in one third. Leave one third white.
Prepare chocolate cake according to box instructions.
Pour 1/3 of chocolate batter into prepared bundt cake pan
Top with white cake batter. Follow with red, then green batter. Finish with 1/3 of chocolate
Do NOT stir batter, just layer each color on top of the other. At the end, when putting the remaining chocolate, don't overfill. Depending on your bundt pan, only pour enough batter to still have room for the cake to rise. It doesn't really matter how much of each color you use.
Bake for 20 minutes or until done. Cool on wire rack and remove from pan.
Divide frosting into 3 microwavable bowls.
Mix one bowl with green food coloring. Stir until desired color is reached.
Mix second bowl with red food coloring. Stir until desired color is reached.
Leave last bowl of frosting white.
Heat each bowl of frosting for 5-10 seconds until frosting is thin and falls off a spoon.
Take a spoon and drizzle one colored frosting over top of cake with a back and forth motion, letting the icing fall over the sides of the cake. Alternate between colors to get desired look. Repeat with all three colors until all frosting is on cake.
Top with sprinkles.
Let cool and serve!