Step 1

Preheat the oven to 350°F. Spray a 9x13 baking dish with baker's spray (Baker’s Joy or generic version)

Step 2

Add the cake mix, water, oil, and egg whites to a medium-sized mixing bowl. Use a handheld mixer on medium speed to mix the ingredients just until combined and no lumps remain. Bake for 25-28 minutes or until a toothpick inserted comes away clean.

Step 3

Allow the cake to cool slightly before using the handle of a chopstick or slim, round wooden spoon to poke holes in the cake ¾-1 inch apart. Allow the cake to cool completely.

Step 4

Add 1 flavor of gelatin to a small heat-safe bowl. (You will need 5 heat-safe bowls) Add ½ cup boiling water to each flavor and stir well until the sugar completely dissolves.

Step 5

Add 5-7 drops of the food color gel to the corresponding gelatin flavor (red food color to the strawberry gelatin, orange to the orange gelatin, and so on). This will make the colors more vibrant.

Step 6

Using either a teaspoon or a drizzling spoon, alternate drizzling just enough of the jello into a hole to color the hole. Do not fill the hole completely up. That will cause the cake to become overly drenched, and you will not get the defined shafts of color you want. You will not use all of the jello; you will have leftovers.

Step 7

Once you have drizzled the different colors, cover and chill the cake in the refrigerator for at least 2 hours.

Step 8

Once completely chilled, remove the cake from the refrigerator. Use an offset spatula or a silicone spatula to smooth the entire container of whipped topping over the cake. Sprinkle with rainbow sprinkles. Slice into 12 slices. Keep the cake refrigerated until ready to serve.