Making a watermelon themed smash cake is the perfect idea for your baby’s ‘one in a melon’ themed 1st birthday party. Not only is a 1st birthday watermelon smash cake super cute, but it’s also pretty easy for a beginner to make! These days, it’s a fun first birthday party tradition to make a small layer cake or other sweet treats like cupcakes and have your baby dig-in with their hands for a fun little smash cake photoshoot session or as the finale to their party.

This watermelon smash cake is ideal for a baby’s 1st birthday party because it has less icing than a typical cake, which reduces the amount of sugar a bit. The sides of the cake in this tutorial are cake that has been colored with food coloring instead of getting its color from a thick layer of icing. It’s also free from any choking hazards you might find in recipes for older kids and adults.

Check out this free printable baby’s 1st birthday checklist for more party ideas!

baby hand grabbing watermelon smash cake

Ingredients
- 1 cup Butter
- 4.5 cups Powdered sugar
- 1/2 cup Milk
- 1.5 cups Flour
- 1.75 tsp Baking powder
- 2 tsp Vanilla extract
- 2 Eggs
- 1 cup Sugar
- Green food coloring
- Black food coloring
- Pink food coloring
Materials
- Bowls
- Spoons
- Piping bags x 2
- Piping tip
- Plastic wrap
- 5 inch round cake pans x3
- Large baking sheet
- Cake spatula
- Electric hand mixer or stand mixer
- Cake board

watermelon smash cake with happy birthday cake topper

How to make an easy watermelon smash cake

Bake cake

Preheat oven to 350 (175 celsius). Cream together 1 cup of sugar and ½ cup unsalted butter. Add in two eggs, and mix in vanilla. In a separate bowl, combine 1 ½ cups all-purpose flour and 1 ¾ teaspoons baking powder. Add the wet ingredients to dry ingredients and mix well. Add milk and stir until the cake batter is smooth.

Separate one-third of the cake batter out and color it green. Add pink food coloring to the rest of the batter. The green cake will be the bottom slice of this watermelon themed cake.

Pour the batter into three greased cake pans. One cake pan will be for green cake, and two cake pans for pink cake. Bake for 20-30 minutes until the cake springs back when lightly touched. Cool cake completely then wrap it in plastic wrap and freeze it.

Trim cake

Make sure you trim the top of the cakes so they are flat and level. Trim the outer ring of the cakes so the size of each cake layer is the same (so it’s not lop-sided). Trimming the border of the watermelon cake also gives it a nice look if you’re not going to cover it up with frosting. The exposed cake is a brighter color and looks cleaner when it’s been trimmed.

Make icing

Make your vanilla buttercream frosting with 1 cup of butter and about 4 cups of icing, 1 tsp of vanilla and 2 tsp of cream or milk. Blend it with a hand mixer or stand mixer until it’s fully mixed and no sugar crystals remain. If you think you’ve put in too much moisture with your milk or cream, try adding a bit more powdered sugar or put your icing in the fridge to firm up if it’s starting to melt.

Frost cake

Take a big spoonful of your icing out into a new bowl and mix in black food coloring. Set aside this black icing for later, you’ll use it as your ‘watermelon seeds’. The rest of your frosting you can color a light pink shade.

Use your favorite piping tip (I used a large star tip) and fill a piping bag with light pink frosting. Put a layer of thick frosting between each cake layer. Then pipe stars or swirls on top of your watermelon smash cake.

pink icing on top of green watermelon themed cake

Decorate cake

Decorate your 1st birthday watermelon smash cake to make it look like there are ‘seeds’ on top of the cake that are still safe for your baby to eat. Do not use anything that could be a choking hazard for your birthday boy or girl.

Dots of black icing are one of the safest options for the watermelon seed decorations. Use a ziploc bag or piping bag and cut a very small hole in the tip or corner of the bag. Add your black icing and as you squeeze out a small amount, use a toothpick to cut the icing stream and apply it to your cake, as seen in my photos.

placing watermelon seeds icing on cake top

Wipe off your toothpick between applying each ‘seed’ so your cake doesn’t get messy with black icing in spots you don’t want it.

Watermelon themed smash cake tips

Real raw watermelon makes for another cute prop during a photoshoot for a watermelon cake smash.
The watermelon theme is perfect for summer parties, if the weather is nice consider having your cake smash outdoors to keep the mess out of your home.
Do not put a lit candle near your baby for their first birthday; they may reach for it and be burned.
Take away the cake after you’ve got a few great photos. A bit of sugar on this special day is totally fine for most kids, but you don’t want to let them consume the entire cake.
Have a second outfit handy and a plan for how you’d like to clean your baby after their cake-smash session.
Do a test with your food coloring brand to ensure it washes off your skin with gentle soap and water. You don’t want to stain your baby’s skin red. I used Wilton Food Coloring and although it did dye my hands, it washed off easily after a soak in warm water.
If you decide to use a cake topper for your cake smash, be sure that it has no sharp edges or points that will end up in your baby’s mouth.

Final Watermelon Cake Smash Thoughts

I hope you’ve enjoyed this easy watermelon smash cake tutorial! For another delicious summer time inspired treat, check out this gluten free peach cobbler recipe! For more summer sweets and fun, you can also make these amazing Cake S’mores on the grill if you don’t have a fire pit.

Save this recipe to your Pinterest for later, or send it to a friend who loves watermelon. Your one year old is just going to love digging into this fun, themed cake made just for them.