I did not grow up going to summer camp. I did, however, consume enough American media to dream of sitting by a campfire making s’mores. I envisioned myself skewering marshmallows onto twigs, toasting them until puffy and golden, then sandwiching them between two graham crackers with a piece of chocolate, all while singing camp songs with my fellow Girl Scouts. The closest I ever got as a child was toasting marshmallows over my parents’ gas stove, which resulted in either sad, under-toasted and unsatisfying marshmallows or singed marshmallows that caught on fire. (My parents were not pleased, and I was permanently banned from toasting marshmallows in the kitchen.)
As an adult, I have had the pleasure of experiencing a real campfire s’more: a gooey marshmallow and warm, just melted chocolate snug between crisp, slightly sweet graham crackers. As someone who lives in an apartment with no outdoor space, though, the campfires are few and far between, so I have to get creative when I’m hankering for those classic s’more flavors. That’s where this icebox cake—a “set-it-and-forget-it” dessert that’s fun and celebratory—comes in. I make it by stacking coffee-soaked graham crackers, homemade chocolate mousse, and whipped cream in a loaf pan, then coating it in a generous layer of Italian meringue, which I hit with a kitchen torch to create a browned, marshmallow-like exterior. It’s a confection that evokes the flavors and textures of a s’more, no campfire or mosquitoes required. Here’s how to make it.
7 Tips for Making a S’mores Icebox Cake That’s Magical, Not Melty
Line your 9- by 4-inch loaf pan with plastic wrap. This cake is made in a standard loaf pan, like the kind you’d use for quick breads such as banana bread. For easy, neat unmolding, line your loaf pan with plastic wrap before you assemble your icebox cake. (For seamless unmolding, make sure the plastic hangs over the edge of the pan so you can easily grab onto it when unmolding. To unmold, remove the plastic wrap from the top of the cake, invert it onto a rimmed baking sheet, and remove the remaining plastic.)
Use layers of graham crackers for a balanced cake that’s not too sweet. The wheaty, bran-filled crackers are an essential part of the classic campfire snack, but I also use them here because they lend an earthy flavor that complements the bitterness of the chocolate and sweetness of the Italian meringue.
Brush the graham crackers with coffee. Most pastry chefs brush their cakes with a layer of simple syrup to keep the sponge moist. Here, I use freshly brewed coffee, which softens the crackers and adds depth of flavor without making the icebox cake cloyingly sweet. Though freshly brewed drip coffee is nice, you can use cold brew, espresso, or whatever you have on hand, including coffee made with instant granules. The coffee can be warm, cold, or room temperature—all work just fine! (Use decaf if you’re worried about the small amount of caffeine.)
Take the time to make your own chocolate mousse. Unlike chocolate ganache, which becomes firm when refrigerated and would make the icebox cake too heavy, chocolate mousse is light and fluffy when cold, making it an ideal filling. Making your own mousse allows you to adjust for sweetness and choose the kind of chocolate you’d like to use. I recommend using chocolate between 64 and 70% cacao, as it results in a mousse that’s not too sweet, but if you prefer a sweeter mousse you could go as low as 40%. If you don’t feel like making your own mousse, you can opt for store-bought chocolate pudding, but your icebox cake will likely be on the sweeter side and the texture won’t be quite as fluffy (but it will still be delicious).
Keep it cold. Refrigerating the cake for at least eight hours allows the crackers to soften to a cake-like texture and all the flavors of the chocolate and cream to meld together. Freeze the cake for at least an hour (and up to one week) after unmolding, as this will ensure it’s cold enough to frost, torch, and slice without melting.
Go with Italian meringue. It may seem a little “extra” to make an Italian meringue for an icebox cake, but I prefer the flavor and thickness of Italian meringue to marshmallow fluff. (But feel free to use marshmallow fluff if you prefer to skip this step.) Making an Italian meringue involves slowly pouring a hot sugar syrup into whipping egg whites, which cooks the egg whites and stabilizes it. As Serious Eats contributor Marissa Sertich Veile explained in her recipe for Italian meringue, sugar is hygroscopic, which means it “binds with water and holds it in place,” and “adds viscosity to the liquid whites, making the bubbles more stable.”
For the toastiest meringue, use a blowtorch. Using a blowtorch allows you to evenly toast the meringue without heating the cake too much. Though I haven’t tried it for this recipe so I can’t guarantee success, you can take a similar approach to that of a baked Alaska and toast the meringue in the oven with the broiler function if you don’t own a blowtorch. Just be sure your cake is adequately frozen before doing so, or you’ll risk melting the cake. You can also leave the meringue un-toasted for a slightly less campfire-ish (but no less delicious!) cake. If you’ve opted for marshmallow fluff instead of meringue, you can torch it too.
For the Chocolate Mousse: In a large heatproof mixing bowl, combine chocolate and heavy cream. Set it over a saucepan filled with 1-inch barely simmering water and heat, stirring occasionally, until chocolate is fully melted, about 10 minutes. Whisk until homogeneous, then remove from heat and set on a heatproof work surface.
Once chocolate mixture is warm to the touch, whisk in 3 egg yolks until well combined. Set aside.
Meanwhile, in the bowl of a stand mixer fitted with the whisk attachment, combine egg whites, salt, and espresso powder. Whisk on medium speed until egg whites begin to foam. Slowly and steadily stream in sugar. Continue to whisk until meringue is glossy and reaches medium-stiff peaks, about 8 minutes. Set aside.
Add 1/4 of the meringue to the chocolate mixture and gently fold until thoroughly combined. Add remaining meringue and continue to gently fold until meringue is almost entirely incorporated, being careful not to overmix. Transfer to large bowl; set aside in refrigerator. Wash and dry mixing bowl.
For the Whipped Cream: In the now-clean bowl of a stand mixer fitted with the whisk attachment, combine cream, sugar, and salt. Whip on medium-high speed until medium-stiff peaks form, about 2 minutes. (Alternatively, combine cream, sugar, and salt in a large mixing bowl. Using a hand mixer fitted with the whisk attachment, beat on medium speed until medium stiff peaks form, about 3 minutes.) Set aside.
To Assemble: Line a 9- by 4-inch loaf pan with plastic wrap. Using a flexible spatula or offset spatula, spread about 1/2 cup (75g) of chocolate mousse on the bottom. Cover surface with 1 layer of graham crackers; you may have to break the cookies up to get them to fit snugly. Gently press them into mousse. Using a pastry brush, brush graham crackers generously with coffee. Using a flexible or offset spatula, evenly spread 1/2 cup (50g) whipped cream across crackers.
Top whipped cream with another layer of crackers and brush with coffee. Using a flexible or offset spatula, evenly spread 1/2 cup of chocolate mousse across crackers. Repeat layering, alternating crackers, mousse and whipped cream as needed, ending with a layer of graham crackers brushed with coffee. (You should have 4 Graham cracker layers.)
Cover tightly with plastic wrap and refrigerate until cake is cohesive and chilled, at least 3 hours and up to 24 hours.
Line a 9- by 13- inch rimmed baking sheet with foil. Remove plastic from top of cake and invert cake onto rimmed baking sheet. Gently peel away remaining plastic, and transfer to freezer until firm enough to slice, about 1 hour or up to 1 week.
Meanwhile, prepare the Italian meringue: In the bowl of a stand mixer fitted with the whisk attachment, begin whisking egg whites on low speed. Meanwhile, in a small saucepan, combine sugar and water. Bring to a boil over medium-high heat and cook until sugar syrup registers 240ºF (115ºC) on an instant-read or candy thermometer, about 4 minutes. (Remove from heat immediately once sugar syrup reaches temperature.)
Increase mixer speed to medium and mix until soft peaks form. With the mixer running on medium speed, carefully and slowly drizzle the hot sugar syrup into the bowl along the side, avoiding hitting the whisk attachment. Increase speed to high and whip until stiff peaks form and meringue is no longer hot, about 10 minutes.
Remove cake from freezer. Using a flexible or offset spatula, frost cake with Italian meringue, using the back of a spoon or spatula to make swooshes. Using a blowtorch, torch meringue 1- to 2- inches away from the surface of the meringue until evenly browned. (To toast meringue in the oven, see notes.) Hold both ends of the foil and gently transfer cake to a cutting board. Wiggle a chef’s knife or long offset spatula under the cake to loosen it from the foil and gently pull foil to remove.
Using a hot knife, slice cake into 8 pieces and serve. (For cleaner cuts, run knife under warm water and dry knife with a clean kitchen towel before portioning each slice.)
Special Equipment
Whisk, stand mixer, 9- by 4-inch loaf pan, pastry brush instant read thermometer, flexible or offset spatula, butane blowtorch
Notes
If you don’t feel like making chocolate mousse from scratch, you can substitute with store-bought chocolate pudding, but the resulting icebox cake will likely be sweeter.
If you don’t own a blowtorch, you can toast the meringue in the oven. However, it is crucial that the icebox cake is fully frozen before you frost it with meringue, otherwise the mousse and cream will melt. Adjust oven rack to middle position and preheat oven to 500ºF (260ºC). After coating the cake with meringue, transfer rimmed baking sheet with icebox cake to oven and bake until meringue is golden brown, about 5 minutes.
If you don’t feel like making Italian meringue, you can substitute with store-bought marshmallow fluff and torch it for a similar result.
Make-Ahead and Storage
The unfrosted icebox cake can be frozen for up to 1 week before slicing and serving. Proceed with step 10 when ready to serve.
Sliced portions can be refrigerated in an airtight container for up to 3 days.