Watermelon Cake with Lime Curd – White cake layers doused in a watermelon simple syrup and layered with watermelon buttercream and lime curd.
Summertime
Who else is so ready for summer? Winter went on way too long around here and I’m not okay with it. To take my mind off the icky weather, I’ve been thinking about all the summer-inspired cakes I want to make. The list continues to grow, so before it gets out of control, I decided to get started with this Watermelon Lime Cake.
I’ve had this cake on my mind for a few reasons:
- Watermelon is the fruit of the summer (in my opinion, that is – I could eat all day, everyday).
- I’ve seen dozens of watermelon cakes around Pinterest but none of them seem to have a watermelon flavor, just the design.
- I wanted to do my own version of a watermelon design.
Cake Brainstorming
As I thought about the cake, I had a hard time settling for just the watermelon flavor by itself. A flavor pairing was calling out to me. The missing part? Lime curd! I immediately felt like the tartness of the lime would contrast and compliment the watermelon flavor so well.
I immediately got to work, but this cake didn’t come together as quickly as some of my other cakes. The cake layers took me a few tries to nail.
Trial and Error
In my first attempt, I used watermelon Jell-O and my white cake recipe for a base. The batter tasted great but the watermelon flavor completely disappeared during baking. In my second attempt, I used the Jell-O mix again and watermelon puree instead of buttermilk as the liquid. Again, the flavor of the batter was great but it baked out again. I thought about using the LorAnns brand of watermelon candy flavoring but after a taste test with my husband and son, we decided it tasted too much like bubble gum. Scratch that idea!
I knew I needed to stick with watermelon Jell-O… but I had to come up with another way for the flavor to stand out more.
Simple Syrup
I decided to think about it some more and after a good night’s rest, I literally woke up at 6 a.m. with the solution in my head. (I must have worked it all out in my dreams! Wish that was the case with more than just my cake problems. Ha!).
Instead of incorporating the flavor into the batter, I would incorporate the flavor into the cake… after it was baked. The solution? A watermelon simple syrup, made with water, sugar and watermelon Jell-O.
The watermelon simple syrup turned out perfectly, and when added to the baked cake layers, gave me the flavor I was looking for.
I also added watermelon flavor to the buttercream – again, using the Jell-O (the candy flavoring wasn’t right and watermelon puree wouldn’t hold up in a buttercream). I love the flavor of the buttercream, especially paired with the cake layers and lime curd.
Overall, I’m so happy with how this cake turned out – both the flavor and the design are exactly what I was going for.
My mom was actually in town when I was going through all my testing and had the chance to sample everything along the way, as well as the final product. She left about a week ago and keeps texting me to tell me how much she loves this cake and how perfectly the flavors go together. (It literally makes me giddy when people can’t forget the way my cakes taste! Best compliment ever!).
This truly is a memorable cake and so perfect for summer. I hope you love it!

I’ve been hobby baking for just under a year and I am so inspired by your work! I can’t wait to start trying some of your recipes, I’m trying the caramel cake today! I do a watermelon cake and also found the loranns oil and jello to not be the greatest BUT I did start using watermelon kool aid squirts to flavour and I absolutely LOVE it! Your Instagram page is one I actually look over daily for inspiration, and now your blog! Thank you 🍰
My Instagram is @cakesontherock
Yeah the oil is not watermelon flavored at all, but I’ve liked the jell-o as a simple syrup. The kool aid idea is awesome too! Thanks so much for following along. xx
Courtney, do I use the entire amount of the simple syrup? And can I use 8 inch pans if that’s what I have? Thx!
No you do not use all of the simple syrup. Just give it a good douse. And you can do three 8″ layers if you want too and use a little more of the syrup.
At what point do you add in food coloring to the frosting? While mixing? After its all mixed?
While mixing 🙂
I live up in Canada and can’t find watermelon jello. Is there something else I could use so it still tastes like watermelon?
You could possibly purchase watermelon jello on amazon or get watermelon extract?
How far in advance can you make the lime curd?