This Jello Watermelon Sheet Cake starts with a cake mix and a box of Jello and comes together in minutes using just one bowl. Honestly, the longest part of it is the baking time! A perfect crowd-pleaser for picnics, or just a fun summer dessert to have around at home. This post contains affiliate links.
Everything about this watermelon cake screams “Summer!” to me. Like pretty much when I look at it, I hear the lyrics “Summer, summer, summertime, summertime …” playing in my head. This is a perfect make and take recipe and there’s no fancy layering of ingredients in the prep. Start with a box of white cake mix, a box of watermelon Jello, dump all the ingredients in a bowl, mix it up and bake!
This recipe was the kickstarter to my signature move of adding Jello to a boxed cake mix. I was invited on a local cable show to demonstrate a spin-off (Tailgate Cake) and the mixer speed got away from me and batter sprayed right in the host’s face. Like zoooom — batter all the places. Click here to check it out in its full glory. Ahh, the memories.
But anyway, this recipe has been a summertime fave for me for years — and May is like summer preparedness season for me, so I hope that tracks for you too!
What Happens When You Add Jello to Cake Mix
You get a pretty colored, lightly flavored cake! No other special modifications needed to the cake mix when you add the Jello in. So, seriously, dump your dry and wet ingredients together in a bowl and mix for two minutes and that’s it for prep. I like to be really literal with my desserts and wanted it to be obvious right away that it was a watermelon cake, so I dropped a few drops of red food coloring in, but totally your choice.
Pour into a greased 9 x 13 pan (I’m partial to Baker’s Joy myself — nothing ever sticks and it doesn’t leave any kind of sticky residue on your pan. Most stores carry it by the Pam) and bake at 350° for 35-38 minutes.
Jello Watermelon Sheet Cake Frosting and Toppers
Then frost away! I used three cans of Duncan Hines Whipped frosting because in my dream world every cake is equal parts cake and frosting, but if you have more reasonable frosting expectations, one frosting can would definitely do the trick. I used 15 drops of food coloring total to get it green and sprinkled the top with some white pearl sprinkles for flair (I got these in a spring sprinkle kit at Meijer, but you can find something similar here.) Then serve it up and enjoy!
This is a favorite recipe hack of mine — I’ve even added Jello to Angel Food Cake Mix with great success! This is definitely a recipe you’ll see more of! Any other combinations you’d like to see/try? I’d love to hear in the comments.
- 1 box of white cake mix
- 1 3 oz. package of watermelon Jello
- 2 eggs
- 1 1/4 c. of water
- 1/4 c. of vegetable oil
- 1-3 cans of frosting
- Red and green food coloring (optional)
- Sprinkles (optional)
- Add the box of cake mix, box of jello, eggs, water and oil into a large bowl. If you'd like to take the cake color up a notch, add a few drops of red food coloring. Mix all on high for 2 minutes. Pour batter into a greased 9x13 pan and pop into a 350° oven for 35-38 minutes.
- Let the cake cool completely and top with 1-3 cans of prepared frosting. I used Duncan Hines Whipped and added 15 drops of food coloring for the green color. Top with sprinkles if you want some flair!
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