Genius Watermelon Cake

READY IN: 36hrs 45mins
YIELD: 1 Cake


  • 2
    cups whole milk, at room temperature
  • 5
    large eggs, at room temperature
  • 1 12
    teaspoons vanilla extract
  • 1
    teaspoon strawberry extract (optional)
  • 5 12
  • 6
    cups sifted powdered sugar
  • 3
    tablespoons baking powder
  • 2
    teaspoons fine salt
  • 1 12
    cups unsalted butter, at room temperature
  • 3 -4
    teaspoons watermelon gel food coloring
  • 1
    lb watermelon Jolly Rancher candies
  • 2
    cups water
  • 8
    ounces mascarpone cheese, at room temperature
  • 1 -2
    teaspoon black gel food coloring
  • 1 -2
    teaspoon leafgreen gel food coloring
  • 2 -3
    teaspoons electric green gel food coloring
  • 12
    teaspoon americolor forest green gel food coloring


  • —Make Your Batter—.
  • Preheat your oven to 350°C Prepare 4 six-inch-round, three-inch-deep (6”x3”) cake pans by spraying the bottom and halfway up the sides with baking spray and placing a baking paper round in the bottom.
  • In a medium-sized bowl, combine your eggs, 1/2 cup of your milk, and vanilla and whisk to combine. Set aside.
  • In the bowl of a stand mixer fitted with the paddle attachment, combine your flour, powdered sugar, baking powder, and salt and mix on low speed for a few minutes until combined. Low speed is important here so as to avoid creating a burst of flour that will get all over your hair and maybe in your eyes, it is the worst.
  • All at once, add in your butter and keep mixing to moisten your dry ingredients creating a crumb-like consistency, about 20 seconds. Begin streaming in your remaining 1 1/2 cups milk, half a cup at a time, continuing to beat on the lowest speed. When all the milk is added, raise the mixer speed to medium and continue to beat the batter for about 30 seconds. This process is important because it incorporates air into your batter.
  • Scrape your bowl with a spatula, and then return the batter to low speed. Add your egg mixture in three batches, allowing each to incorporate fully before adding the next. Add 1 teaspoon of Watermelon food gel and beat again on medium for about 20 seconds. If you’d like to achieve a deeper color, add another 1/2-1 teaspoon of gel coloring and beat on medium to combine.
  • Divide your batter between your four prepped pans and smooth the batter to level it. Bake for 40 minutes, then keep a close eye on your cakes for the next 5-7—you’ll want them to bounce back when you press on the middle of the top of the cakes. You can also insert a cake tester, and it should come out clean with at most a few crumbs clinging to it.
  • Remove your cakes from the oven and allow them to come to room temperature on a rack. Then, I like to wrap them up in plastic and put them in the fridge for at least half an hour, preferably overnight before I remove them from the pans. These cakes should rest in the fridge for at least 8 hours total before stacking.
  • —Make Your Watermelon Simple Syrup—.
  • Place your water in a medium saucepan and add your unwrapped jolly rancher candies. Bring the water to a boil, then reduce to a simmer, stirring occasionally until the candy dissolves completely. Simmer for an additional 10 minutes, then set aside to cool to room temperature.
  • —Prepare Your Buttercream—.
  • Whip up some Milkmoon Meringue Buttercream (recipe #536136), you'll need 2x the amount listed in the recipe. Reserve 5 cups of this buttercream for your filling, and set the rest aside.
  • Combine the 5 cups buttercream with your mascarpone, beating well to combine thoroughly. Add drops of Watermelon food coloring gel until you reach the same shade as the cakes you baked (cut a small amount off the top of one of your cakes to take a peek at the color inside).
  • Take 1/2 of your reserved white buttercream and add Super Black food gel into it until you achieve a strong black. Hot tip: this color will deepen as it stands. Set aside.
  • —Prep Your Layers—.
  • Start by trimming the domes off your cakes. We want flat disks of cake so we can accomplish a tall build!
  • Now torte your layers out. Torting is the process of cutting a large cake into smaller layers, and I like to torte my layers super thin. You can choose instead to just trim the domes and leave the cakes as-is for a four-layer cake, or torte each cake in half for eight layers. The more layers, the cooler the seed affect in the slice reveal, however!
  • —Build Your Cakes—.
  • Prepare two disposable piping bags, one filled with your black buttercream and the other with your red. Cut off the tips of each to create a hole that is roughly 1/8 of an inch wide, fairly small.
  • Using a turntable as a base, center your first layer on an 8” round cake drum with a small dab of buttercream in the middle to anchor the cake. Brush the layer with a small amount of jolly rancher syrup. Then, pipe a spiral of buttercream in the very middle of the layer, measuring about 1-1 1/2 inches wide. Smooth this buttercream, then pipe another spiral of buttercream starting about 1/8 inch away from the buttercream at the center, and extending all the way to the edges of the layer.
  • Pipe your black buttercream into the opening left, creating a black ring in the middle of the layer. Smooth your red buttercream, being careful not to disturb the black ring. Place your next layer of cake on top, doing your best not to drag it around too much as you center it. Repeat until you reach your final layer of cake, at which point you can wrap the whole thing in plastic and refrigerate stack until firm, at least an hour.
  • Remove from the refrigerator when the cake doesn’t wiggle when you shake it, and place it on a turntable on the counter. Using a serrated knife, go around the cake trimming off those crusty sides. Wrap the nude cake in plastic, and put it back in the refrigerator.
  • —Frost Your Cake—.
  • You can start by crumb-coating the sides of your cake with a small amount of your white buttercream and refrigerate 10-20 minutes to set, or skip the crumb coat if you’re confident diving right inches Leave the top un-coated! This will help with the watermelon slice illusion.
  • Begin frosting your cake by placing about a 1/2 cup dollop of buttercream on top of your cake, and smoothing it out to the edges, making sure the buttercream overhangs the edges of the cake by at least 1/2 inch all the way around. Refrigerate until the buttercream is firm. Using a paring knife, trim the buttercream back so it’s perfectly flush with the sides.
  • To create the white layer of rind, place about two cups of your white buttercream in a disposable piping bag and cut a 1/4 inch hole in the end. Pipe the buttercream in rings up the entire cake, making sure to over-pipe at the top so the white buttercream sticks up in a ring around the top. Use a straight-edge to smooth your buttercream on the sides—I use a 14” quilting ruler!—and refrigerate about 10-20 minutes.
  • Take your remaining white buttercream and, using mostly Electric Green with a few squeezes of Leaf Green to deepen, create a bright green watermelon rind color.
  • Repeat the piping process with the light green buttercream, working your way up the sides and then smoothing them down. Put the cake back in the refrigerator to firm up.
  • —Paint Your Rind—.
  • Melt down your remaining green buttercream in the microwave until it’s a paintable consistency. Stir in more green coloring, including a few drops of Forest Green to deepen the hue. Using a flat or fan brush, brush your buttercream up the sides of your cake, creating loose, imperfect stripes. You can go for perfection if you like! You’ll get a more cartoonish, less realistic look to your watermelon cake, which can be fun too. When you’re finished, put the cake in the fridge again.
  • —Trim the Top—.
  • After 10-20 minutes when the buttercream is totally firm, use your paring knife to trim the white and green buttercream down from around the top of the cake, making it totally flush with the smooth watermelon red buttercream on the top. You’ll reveal a perfectly smooth watermelon cross-section that will have your guests scratching their heads!
  • Pipe about eight black seeds in a circle around the top using an Ateco 8” round tip, piping teardrop shapes by piping a small pearl and drawing it to the center while releasing pressure on your bag.
  • —Drumroll, Please!—.
  • Create a picnic spread and get ready to blow your guests’ minds—it’s time to slice your watermelon! Using a non-serrated knife, line the point up with the middle of the cake and, holding the knife completely level, slice down in a clean, confident motion until you hit the board. Remove the knife, wipe with a paper towel, and repeat to cut a slice that is perhaps 1/4-1/5 of the entire cake if you want it to be able to stand freely. Then, push an offset spatula under the slice, and lift up, using your other hand to stabilize the top of the slice. Pop the slice out from the bottom up, and remove to reveal… a slice of watermelon, complete with seeds and a perfect rind!
  • Enjoy!