Preheat the Oven and Prepare Your Cake Pans - Preheat your oven to 350 degrees Farenheit. Grease your 8 or 9-inch cake pans with cooking spray.
Prepare the Chocolate Chips - In a small bowl, mix 1/2 cup of the chocolate chips with one tablespoon of cake mix.
Prepare the Cake Mix - In a large mixing bowl, add the rest of the cake mix, water, vegetable oil, egg whites, and soft drink mix. Beat the mixture at low speed for 30 seconds, using an electric mixer. Then, change the speed to medium and beat for two minutes.
While mixing, also scrape the bowl as needed with a rubber spatula. Once the batter is completely mixed, add in the chocolate chips. Gently incorporate them into the batter with the rubber spatula.
Bake the Cakes - Pour the cake mix evenly into the two cake pans. Bake for 29-34 minutes for two 8-inch cakes and 25-30 minutes for two 9-inch cakes.
To check if the cakes are done, stick a toothpick in the middle of the cake. If the toothpick comes out clean, the cakes are done, if there are crumbs or batter on it, continue to bake the cakes. Once done, allow the cakes to fully cool on a wire rack.
Prepare the Frosting - Take one cup of the white frosting and add it to a small bowl. Mix in 10-12 drops of green food coloring. For the remainder of the frosting, add 10-12 drops of red food coloring.
Decorate the Cake- How to Make it Watermelon - Apply a thin layer of red frosting to one cake and then stack the other cake on top. Decorate the top of the cake with the remainder of the red frosting. Frost the sides of the cake with green frosting.
Add the remainder of the chocolate chips to the top of the cake. Then, add the green jelly beans to the side of the cake. Slice and serve.