Rainbow Jello Cake

5 from 4 votes

Rainbow Jello Cake is unbelievably simple to make using a box of cake mix and jello for an effortless treat that is full of flavor and color. Perfectly pretty for rainbow parties and special celebrations.

Prep Time20

Cook Time28

Chill and Rest Time2 30

Total Time3 18

Course: Dessert

Cuisine: American

Servings: slices

Calories: 317kcal

Author: Jennifer Fishkind

Ingredients

15.25 ounces box of white cake mix
1 cup water
½ cup vegetable oil
4 egg whites room temperature
3 cups boiling water
3 ounce box of strawberry gelatin mix
3 ounce box of orange gelatin mix
3 ounce box of lemon gelatin mix
3 ounce box of lime gelatin mix
3 ounce box of berry blue gelatin mix
Red, orange, yellow, green, and blue food color gel
8 ounce container of whipped topping thawed
Rainbow sprinkles optional garnish

Instructions

Preheat the oven to 350°F. Spray a 9x13 baking dish with baker's spray (Baker’s Joy or generic version)
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.
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.
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.
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.
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.
Once you have drizzled the different colors, cover and chill the cake in the refrigerator for at least 2 hours.
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.

Notes

Storage:

To Store: Store any leftovers covered in the refrigerator for up to 3 days.
To Freeze: You can freeze the un-topped rainbow jello cake for up to 3 months. Allow the cake to thaw in the refrigerator overnight before topping it with the whipped topping and rainbow sprinkles.

Tips:

You can substitute any flavor of gelatin for the gelatin listed in the recipe.
You can use the leftover gelatin to make gelatin squares or even use small-shaped cutters (like stars, hearts, or other shapes) to garnish the top of the whipped topping instead of rainbow sprinkles.
I used the end of a chopstick to poke the holes in the cake, but you can use the back of a wooden spoon, a straw, toothpick, fork etc. You may have smaller or larger holes.
You must let this cake cool the full 2 hours for the jello to set properly, otherwise you may end up with a soggy bottom.

Nutrition