Watermelon Cake

My life was forever changed one summer evening during a backyard bbq. A few families had come over for a get together around the campfire with hotdogs, burgers, and s’mores and one family brought a salad. Not just any salad…it was a watermelon salad. Chunks of fresh sweet juicy watermelon, cubes of salty savoury feta cheese, and sprigs of garden-grown mint.

Despite the dairy, I forged ahead with a scoop and oh silent night it was insanely delicious. I never would have thought to put those flavours together but they worked beautifully. And that, my sweet cake friends, was the beginning of a fun flavourful Watermelon Mint Feta Cake!

Note: This post contains affiliate links to which I earn a small commission, but don’t worry there’s no extra cost to you! Thank you for supporting CAKED by Katie.

Watermelon Experiments

Watermelon is a tricky flavour. It’s hard to nail down a genuine flavour without it either being 1) weak or 2) fake. I hummed and hawed over how to create watermelon flavour in this cake and actually tried out a few different cake and filling recipes.

I settled on using real watermelon fruit juice and reducing it to concentrate the flavour as I did in my guava cake. This keeps the true watermelon flavour but intensifies it. And with an added teaspoon of watermelon flavour to give it a friendly but not overly fake boost I think I achieved a great flavour. This reduced watermelon juice is used in both the cake layers and the filling.

Feta: It’s Worth The Pain

I’m dairy intolerant. My tummy is not a happy camper when I eat anything that has dairy in it. Not just lactose, but any and all dairy. I was diagnosed with a dairy allergy back when I was probably 10 or 11 and have pretty much steered clear of all dairy since then.

Now here comes the but. But…I will indulge every few blue moons when I know it’s going to be worth it. And this mint feta buttercream…it was worth it. Using crumbled goat’s milk feta cheese, I added it to my vanilla mint buttercream. And let me tell you, folks…it was worth every tummy cramp that followed. Salty, minty, savoury, and sweet. Mmmmmm. It balanced beautifully against the sweet watermelon cake layers and filling.

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Watermelon Mint Feta Cake

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  • Author: Katie
  • Total Time: 2 Hrs 30 Mins
  • Yield: 10 Slices 1x


Sweet watermelon cake packed full of genuine watermelon flavour and surrounded in a sweet and salty feta mint buttercream. The perfect summer BBQ dessert.




  • ⅓ cup dairy-free butter, room temperature

  • 1 ½ cups granulated sugar

  • ½ cup egg whites (approx 4 egg whites), room temperature

  • ¼ cup dairy-free yogurt

  • 1 tbsp. vanilla extract

  • 1 tsp. watermelon flavour

  • 2 ½ cups cake flour, sifted

  • 1 ½ tsp. baking powder

  • ½ tsp. baking soda

  • 1 tsp. sea salt

  • ⅔ cup watermelon juice, reduced *make sure it’s 100% watermelon juice

Watermelon Filling:

  • ¼ cup granulated sugar

  • 1 ½ tbsp. cornstarch

  • ¾ cup watermelon juice, reduced and divided

  • 1 tbsp. lemon juice

  • 1 tbsp. dairy-free salted butter

Mint Feta Buttercream:

  • 1 cup dairy-free salted butter, room temperature

  • 1 cup vegetable shortening

  • 8 cups icing sugar

  • 1 cup crumbled goat feta cheese, room temperature

  • 1 tbsp. vanilla extract

  • 1 tsp. mint extract

  • 1 tsp. fine sea salt

  • ¼ cup dairy-free milk

  • optional: green gel food colour * I used ChefMaster




  1. Preheat oven to 350 degrees and prepare three 6-inch round cake pans.

  2. Bring 3 cups of watermelon juice to a boil and reduce heat to low and allow to gently simmer. Remove from heat after quantity has reduced in half, approx. 10 minutes. Let cool while mixing up the cake batter.

  3. In the bowl of a stand mixer cream butter and sugar on high for 1 minute.

  4. Add egg whites and mix on high for 2 minutes.

  5. Add the yogurt, watermelon flavour, and vanilla extract and mix on high for 2 minutes.

  6. Combine all the dry ingredients into the mixer and mix on low

  7. While the mixer is on low slowly pour in ⅔ cup of reduced watermelon juice and mix until combined. Be careful to not overmix the batter.

  8. Divide batter between pans and bake for 20-25 minutes or until a toothpick comes out with a few crumbs.

  9. Cool in pans for 10 minutes and then invert on a cooling rack to fully cool.

Watermelon Filling:

  1. In a medium pot combine sugar, cornstarch, and ½ cup of reduced watermelon juice and mix until smooth.

  2. Cook mixture on medium-low heat constantly stirring until mixture thickens and comes to a boil. Let boil for 1 minute and remove from heat.

  3. Add in the remaining ¼ cup of reduced watermelon juice, lemon juice, and butter and stir until melted and fully combined.

  4. Let fully cool before filling the cake.

Mint Feta Buttercream:

  1. In the bowl of a stand mixer with the paddle attachment beat the room temperature feta cheese until smooth.

  2. Add in the butter and shortening and beat on high speed until light and fluffy.

  3. Add the icing sugar, salt, mint extract, vanilla extract, and milk and mix on low until combined.

  4. Turn the mixer up to medium and let mix for 5 minutes until smooth and creamy. Scrape the sides of the bowl when necessary.

  5. Add a drop of green gel food colouring if so desired.

Cake Assembly:

  1. Place one leveled layer of watermelon cake on a cake board or plate. Top with approximately 3/4 cup of buttercream.

  2. Pipe a border of buttercream around the edge and fill with approximately 1/3 cup watermelon filling. Repeat with the remaining layers and apply a thin coat of buttercream all over the cake. Refrigerate for 20 minutes.

  3. Cover the cake with another layer of buttercream and smooth sides.

  4. Decorate as you please. I left the top edge raw and unfinished for a rustic aesthetic and used frozen watermelon chunks, crumbled feta cheese, and fresh mint sprigs to decorate a top border. Enjoy.

  • Prep Time: 2 Hrs
  • Cook Time: 30 Mins
  • Category: Cakes
  • Cuisine: American

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  1. Wow. This turned out so good. I did not use dairy free products or the buttercream but the cake and filling were fantastic. Highly recommend trying this out.

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