No cookie cake pan? No problem! This fun watermelon cookie cake starts with my famous chewy cookie cake recipe...but baked in a 9x13" pan. Simply cut it into wedges, then decorate with pink frosting, a ruffled green rind, and mini M&M's for the seeds!
Reader reviewS ★★★★★
"The reviews did not lie, this recipe is INCREDIBLE and so fast and easy!" - Katie
Love love LOVE. Soft and chewy! - Amanda
"Amazing cookie recipe. I strayed away from this recipe to try a few others and none turned out good! I sell mini cookie cakes in my farm stand with this recipe and they are one of the first to sell out!! So good." - Ashley
How cute are these?! 🍉
These are my new go-to for July 4th, summer birthdays, pool parties, and end-of-school celebrations. One pan feeds a crowd, it travels well, and kids love helping with the seeds.
Here's why I love them:
- No fancy decorating neded: No fancy cookie cutters or elaborate decorating skills needed.
- Feeds a crowd: One 9x13 pan cuts into 14 watermelon slices!
- Two ways to make them: Cut into slices and decorate individually, or frost the whole pan pink for the easy version!
what you need
Supplies & Decorating Tips
- 9x13" Pan
- Cookie Dough (recipe below)
- Frosting (recipe below)
- Piping Bags (I use these tipless ones so that you don't need couplers or round piping tips)
- Wilton 32 Tip (for the ruffled green rind. You can find these cheaper at craft stores - Amazon is a bit pricey)
- Food Coloring
- Mini M&M's for the seeds
How to Make a Watermelon Cookie Cake
The whole process comes down to three easy steps: bake and cool, cut, then decorate.
Color Frosting
Divide the frosting and tint with Chefmaster gel colors using my formulas below. To prevent making them too dark, dip the end of a toothpick into the gel to color a little at a time and mix fully before adding more.
- Pink: ¾ cup frosting + 2 toothpick swipes of Deep Pink, 1 swipe Yellow, and a tiny swipe of Orange.
- Green: ½ cup frosting + 2 drops Royal Blue and 1 drop Yellow (double for darker shade). I used a Wilton 32 star tip for the ruffled green rind.
- Yellow: ¼ cup white frosting, leave untinted
Step 2: Cut Into Slices
- Slide the cooled cookie cake out of the pan using the parchment overhang.
- Cut the rectangle in half lengthwise so you have two long strips.
- Cut each strip into triangles by slicing on the diagonal, alternating the direction of your knife. You should get 14 slices.
Tip: Refrigerating the cooled cookie cake for 15-20 minutes will help achieve the cleanest edges.
Step 3: Decorate
- Flesh: pipe the pink frosting across each triangle, leaving about 1" of space on top.
- White ring: pipe a thin line of white frosting just above the pink (a tipless piping bag with the tip cut off or a Wilton 10 works well).
- Rind: finish the top edge with a ruffled band of green frosting using a Wilton 32 tip.
- Seeds: press a few mini M&M's into the pink frosting.
Let them set for a few minutes so the frosting firms up before serving or transferring.
Other ways to decorate!
Short on time? Skip the cutting and shaping. Leave the cookie cake whole in the pan, frost the entire top with the pink frosting, add a green border around the edges for the rind, and scatter mini M&M seeds across the top.
Cut into squares to serve. You get the same watermelon look with less effort, which makes this a great option when the kids are decorating.
melissa's tips
Tips & Variations
- Color gradually. Watermelon pink is made with the TINIEST amount of gel food coloring, so dipping a toothpick in the gel is the best method to avoid making it too bright.
- Press the m&m's on quickly: This frosting starts to firm up after about 15 minutes, so it's best to put on the m&m's directly after piping.
- Make ahead: This cookie cake is best fresh but can be baked up to 1 day in advance. Store leftovers airtight at room temperature up to 3 days.
Frequently Asked Questions:
Totally! For a 11" round cookie cake, I recommend baking for 11-12-14 minutes as instructed in my original cookie cake recipe.
Mini M&M's are my favorite, but mini chocolate chips or pieces of dark chocolate work for the watermelon seed look.
One 9x13 cookie cake makes 14 watermelon wedges, enough for a party or potluck. If you have my cookbook, One Crafty Pan, you can also use the "Triangles" cutting diagram on Page 16 to make them smaller and yield more!
Looking for more summer desserts?
Watermelon Cookie Cake (with a 9x13" pan!)
Ingredients
⭐️ Before you begin! If you make this, will you do me a huge favor afterwards and leave a review and rating letting me know how you liked this recipe? This helps my small business thrive so I can continue providing free recipes and high-quality content for you.
Instructions
- Preheat the oven to 350°F. Grease and line a 9x13 pan with parchment.
- In a large microwave-safe bowl, melt ½ cup unsalted butter for 20 to 30 seconds, until fully melted.
- Add ½ cup light brown sugar and ¼ cup granulated sugar and mix until combined. Add 1 large egg and 2 teaspoons vanilla extract, then stir.
- Stir in the ½ teaspoon baking soda, ¼ teaspoon baking powder, and ¼ teaspoon kosher salt. Add the 1 ½ cups all-purpose flour and stir until combined. Fold in 1 cup semi-sweet chocolate chips.
- Press the dough evenly into the prepared pan. Bake at 350°F for 12 to 14 minutes, until slightly brown on top and slightly underbaked in the center.
- Cool completely. For clean slices, cool in the pan, then chill in the fridge for 30 minutes before cutting.
- Beat the softened ½ cup unsalted butter on medium-high speed for 2-minutes until smooth. Turn the mixer to low speed then slowly add 2 ½ cups powdered sugar. You may need to stop and scrape down sides. Add 2 teaspoons vanilla extract and a pinch kosher salt and turn mixer to medium speed. One tablespoon at a time, add 2 to 4 Tablespoons milk. Beat on high for 2-3 minutes until creamy and the frosting is at a good consistency to pipe. If it looks too runny, add more powdered sugar. If it looks too stiff, add a tiny bit of milk until you get to the desired consistency.
- Lift the cooled cookie cake out of the pan using the parchment.
- Cut the rectangle in half lengthwise so you have two long strips. Cut each strip into triangles by slicing on the diagonal, alternating the direction of your knife. You should get 14 wedges. A diagram is provided in the blog post above.
- Pipe the pink frosting across the wide top of each triangle, leaving about 1" of the straight edge bare. Next, pipe a thin line of white frosting just below the pink (a Wilton 10 tip works well). Finish the top edge with a ruffled band of green frosting using a Wilton 32 tip.
- Press a few brown mini M&M's into the pink frosting.
- Store in an airtight container for 2-3 days. This is best eaten within 2 days for best freshness.
Did you make this?
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How cute are these!! I was short on time, so I chose to decorate the full cookie. They’re soft and chewy - the frosting is light and not super sweet. Next time I’ll cut then frost so I can display my incredible creation!
Super cute and delicious!
Cute and yummy cookie! My granddaughter and I made these today. She had fun frosting them! #BakeandTake #DeaignEatRepeat
Very fun to make but my decorating skills could use some work. Cookie was chewy and delicious
Fun, festive, and a family favorite - LOVE this recipe!
We actually used your sugar cookie bars as the base, but my 9 year old did the decorating :) they were a hit!
Absolutely delicious. Anything cookie cake by Melissa is a great addition to your dessert repertoire!
Such a fun recipe! We LOVE all cookie cake recipes by Melissa! The absolute perfect texture, so easy to make in a 9x13 pan, and I appreciate that the frosting isn’t overwhelmingly sweet, just the perfect amount!
So delicious! Our family’s all-time favorite chocolate chip cookie recipe is Melissa’s one bowl chocolate chip cookies. This cookie cake is basically a pan full of those cookies, with way less work and time it takes to bake because you don’t have to scoop out individual pieces! And Melissa’s frosting is always not too sweet, which is preferred for our household!