Watermelon Cake Tutorial

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Today I'm going to show you how to make the most adorable buttercream Watermelon Cake and Cupcakes! These fun summertime designs are so CUTE, and you'll love how simple they are to create!

Simple Watermelon Cake & Cupcake Tutorial by MyCakeSchool.com!



It's time for some summer fun! We're actually a couple of days shy of the official first day of summer but the kids are out of school, the pool is open, & it's HOT-- so in my book, summer is well underway ;0)

When I think of summertime cake ideas, watermelon is one of the first themes that pops into my head...and somehow I've never made a watermelon cake tutorial before.  Today is the day!  We're going to show you how to transform a simple sheet cake into an adorable slice of watermelon-- and we're throwing in couple of matching cupcake designs too.

First, I started with a 9x13" sheet cake.  (Mine is one layer but of course this design works just fine with a double layer!)

I trimmed away the two bottom corners with a slight curve, as you can see below.  I also scooped away a "bite" on top of the watermelon.

*When possible (and especially if working with a soft cake), I like to do my cake carving when the cake is at least partially frozen.  If your cake is dense, room temperature cake is fine for carving.


CUTE Buttercream Watermelon Cake Design by MyCakeSchool.com! Free Cake Tutorial!

Next, I frosted my cake with our Classic Vanilla Buttercream Frosting tinted with Americolor Deep Pink. (I carried the pink frosting across the top side of the cake also.)


The cutest watermelon cake and cupcakes! Free tutorial by MyCakeSchool.com!

Smooth the frosting however you'd like.  I used the "Hot knife" method of smoothing, so I dipped my spatula in very hot water before gliding it across my pink frosting.

Then, I frosted around the bottom edge/side of the cake with buttercream tinted Americolor Electric Green.


Adorable Watermelon Cake Tutorial by MyCakeSchool.com! This simple sheet cake design is SO easy and perfect for summer parties!


I swooped in with my trusty spatula at an angle and lifted away the excess icing.  I wanted a nice smooth/flat surface for the ruffles I'm about to add.


The CUTEST Watermelon Cake Tutorial by MyCakeSchool.com! Perfect for summer entertaining! Free Tutorial!

Practice makes perfect!  Especially when you're having trouble envisioning what a ruffled rind will look like ;0) --

My ruffled rind is piped with a large Wilton 125 petal tip (green frosting), and a smaller Wilton 104 tip (white frosting).

Cute Watermelon Cake and Cupcake Tutorial by MyCakeSchool.com! Free tutorial! This idea is perfect for summer birthdays or parties!


Here we go!  You can see that I allow just a very slight overhang with my ruffles.

If you've never made ruffles before, just remember that the small end of the teardrop shaped piping tip is going to be facing out...and the opening is parallel to the surface of the cake as you move the bag slightly up and down to create the ruffles.  This description will make much more sense as you are doing it.


Now, our rind is complete!  Two rows of green, piped with a Wilton 125...and one row of white, piped with a 104 tip.  My seeds are oversized chocolate chips, but fondant would have worked nicely too!

These ADORABLE Watermelon Cake and Cupcake Designs are perfect for summer entertaining! Free step by step cake tutorial by MyCakeSchool.com.


Since I used a crusting buttercream, I was able to impress "teeth marks" into the bite out of the watermelon.  I did this using the fat handle of a "cake paintbrush" of mine, but you can improvise with whatever you can find around the kitchen.


The BEST Watermelon cake and cupcake tutorial by MyCakeSchool.com! SO much fun and perfect for summer!

Next, I made some cute little cupcakes!  The pink is piped with a Wilton 12 tip, spotted with mini chips, and then ruffled with a small petal tip.


CUTE Watermelon Cake and Cupcake Designs by MyCakeSchool.com! This free tutorial is so simple and perfect for summer!

Another simple watermelon design is create ruffles in alternating shades of green.  Again, I used a small petal tip for these green shades!

Adorable Watermelon Cake and Cupcakes in Buttercream! Free Step by Step cake and cupcake tutorial by My Cake School!


Here's our cake and cupcakes!! As a final detail, I piped small pink dots on top of my pink frosting with a Wilton 3 tip but this is completely optional.  This was such a fun cake to make, I hope that you try it out this summer!!



The CUTEST Watermelon Cake and Cupcake Tutorial by MyCakeSchool.com! These fun buttercream cake and cupcake designs are so easy and perfect for summer!



Update June 2019- Looking for more Watermelon Cake fun? We've just added a Watermelon "Fault Line" Cake video to our free cake tutorial section! This was such a fun cake to make, and it's an all-buttercream design that can be changed up to fit all sorts of themes.  You can find it here!: Watermelon Fault Line Cake


Watermelon Fault Line Cake- Free Video Tutorial






Thanks for stopping by! Don't forget to check out our full collection of favorite recipes for cakes, cupcakes, and frostings in our Recipes Section!  Or, for more FUN free cake tutorials and free cake videos, check out our Free Tutorials Section!

Happy Baking!

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  1. Lovely watermelon cake!
    You gave clear directions that I think I can even follow for a great, impressive cake.
    I would love to see how to make a basket weave cake.
    Great blog!