My mom first made this dessert at some time during my childhood. It was as awesome then as it is now, and it inspired a lifelong affection for raspberry sorbet topped with chocolate chips, aka watermelon seeds. It’s simple in that it only requires four ingredients, but it is a little complicated in terms of technique — you’re working with melty ice cream (often in the summer heat), and that can turn things sticky. Crazily enough, Phoebe and I made this in the makeshift condo kitchen on our spring break trip to Costa Rica a few years ago, somehow serving it to twenty friends before it melted.
I think it’s become harder to find green ice cream or sherbet recently. We used to buy a cheap, unbranded gallon of pastel green lime sherbet from the supermarket, but apparently health consciousness has done away with the availability of that. My mom’s friend Renee suggested using green tea ice cream, which she found at Walbaum’s. After spending a while at the freezer case, I wound up buying three cartons of Edy’s Spumani ice cream and fishing out the green pistachio from the strawberry and chocolate that shared the gallon. The pistachio tasted delicious, so it was all for the best. Worst case scenario, you can use vanilla — just dye it green with food coloring before using. And don’t criticize me for using fake green ice cream. This cake is worth it. Just imagine the delight of your sisters or guests when you slice into this big round green thing to find it looks just like a watermelon, and tastes even sweeter.
You can modify this recipe according to what you have. If your bowl is smaller, reduce the quantities; if larger, increase them. Just be sure to clear a space in the freezer for the bowl you choose, and make sure that space also fits whatever platter you serve the cake on. On the off chance that there are leftovers.
Clear a space in your freezer that will fit the bowl you’re using. I like to turn down the freezer temperature a notch or two.
Leave the green ice cream out on the counter until it reaches an icing-like consistency. You want it to be easy to spread, but not at all liquidy.
Meanwhile, cover a 10-12 cup bowl with overlapping sheets of tin foil.
Spread the softened green ice cream evenly across the bowl. If it starts to slide down from the top edges, freeze it for 30 minutes or so, then press it into place. Freeze the bowl for about 2 hours, until the ice cream is quite hard.
While the green layer is chilling, soften the lemon sorbet. Spread a thin layer across the surface of the green ice cream, smoothing to cover it completely. Freeze again, until the lemon sorbet is hard.
Soften the raspberry sorbet and place it into a large bowl. Sprinkle in the chocolate chips and stir to distribute them evenly.
Remove the green and white watermelon cake from the freezer. Spoon the raspberry sorbet into the cavity and smooth the top. Cover with plastic wrap, then a tight layer of tin foil. Freeze overnight.
When you’re ready to serve, invert the cake on a flat serving platter. Lift off the bowl, then carefully peel off the foil. Smooth the cake with a plastic spatula dipped in warm water before. Serve immediately — quick, before it melts!
To store the cake, flip it back into the bowl in which you made it. Cover with plastic wrap and foil and freeze.