The flavors of this iconic campfire dessert — no kindling required — can now be enjoyed year-round, thanks to this cake. There’s no way you can miss with the combination of chocolate, marshmallow, and Graham cracker. This cake is extra special, with both pudding and whipped cream layered throughout. — Jean Sagendorph and Jessie Sheehan, authors of Icebox Cakes: Recipes for the Coolest Cakes in Town.
In a medium bowl, whisk together both flours, the baking soda, and salt and set aside. In a small bowl, combine the milk and vanilla and set aside.
In the bowl of a stand mixer fitted with the paddle attachment, cream the brown sugar, butter, and vegetable oil on medium-low speed until slightly fluffy, about 2 minutes. Be careful not to overbeat. Scrape the sides of the bowl with a rubber spatula. Add the honey and mix until just incorporated and scrape the bowl again. The mixture may look a bit curdled at this point; that's okay.
With the mixer running on medium-low speed, add half of the flour mixture. Stop the machine and scrape the sides of the bowl. Return to medium-low speed and add the milk mixture, then the remaining flour mixture. Beat until the dough is still crumbly, and not yet a cohesive mass. Scrape the sides of the bowl to fully incorporate all the ingredients.
Form the dough into two 2 1∕2-by-5-inch blocks (or line an 8-by-4-inch/20-by-10-centimeter loaf pan, preferably with straight sides, with plastic wrap and press the dough into the pan, forming one large block), wrap the blocks (or pan) in plastic wrap, and freeze them for at least 2 hours, or overnight. (If you choose to press your dough into a loaf pan to shape it, your crackers will be slightly smaller than the traditional cracker size.)
Line two baking sheets with parchment paper.
Once frozen, unwrap one block of dough and use a sharp paring or chef’s knife to cut it into thin rectangular slices about 1∕8 inch thick. Do not be concerned if your rectangles are imperfect. (The crackers will be buried inside the cake and no one will know.) Using the tines of a fork, prick the rectangles lengthwise in two rows.
Arrange the slices about 1 inch apart on one of the prepared baking sheets and place them in the freezer for at least 10 minutes. Repeat with the second block of dough and prepared baking sheet. If you need more room to fit all of your dough slices, simply arrange them on additional sheets of parchment paper, layer the dough-covered papers one on top of the other on the second baking sheet in the freezer, and switch them out as you bake off each batch. (You can also wrap the baking sheets in plastic wrap and freeze the slices for up to 1 week.)
Position a rack in the center of the oven and preheat to 350 degrees F.
Place one baking sheet of frozen dough slices in the oven and bake until they are golden brown and relatively firm and dry, 13 to 15 minutes, rotating the sheet halfway through the baking time. Using a stiff metal or plastic spatula, immediately press down lightly on each cracker to flatten it. Let the crackers cool on the baking sheet for 2 to 3 minutes, then transfer them to a wire rack to cool completely. The crackers should be very crispy when cooled. If they are not, place them back in the 350 degrees F oven for 1 to 2 minutes more. Repeat to bake the additional sheets of frozen dough slices.
Store the crackers in an airtight container as soon as they have cooled. They will remain crispy at room temperature, tightly sealed, for about 24 hours. Freezing the baked crackers in a resealable plastic bag for up to 1 month also works well. There is no need to defrost the crackers before assembling your cake.
In a medium saucepan, combine the granulated sugar, cocoa powder, cornstarch, and salt. Add the milk and cream and whisk to combine. Add the egg, whisk again, and place the saucepan over medium-high heat, whisking constantly.
Once the mixture begins to thicken and bubbles begin popping on the surface, turn the heat to medium and whisk vigorously for 45 seconds. Remove the pan from the heat.
If the pudding has any lumps, strain it through a medium-mesh wire sieve into a heatproof bowl. Add the butter and vanilla and whisk until they are incorporated.
The pudding should be used almost immediately; it should still be warm and relatively pourable when you layer it with the crackers.
In the bowl of a stand mixer fitted with the whisk attachment, whisk together the egg whites, cream of tartar, and salt on medium speed until quite frothy. Add the 1 tablespoon granulated sugar and whisk until soft peaks form. The peaks should flop over when the whisk is lifted. Be careful not to overbeat.
Meanwhile, in a small saucepan over medium heat, combine the remaining ¾ cup granulated sugar, corn syrup, and water. Using a wooden spoon or heat-proof spatula, gently stir the mixture until the sugar dissolves completely. Attach a candy thermometer to the side of the pan. Increase the heat to medium-high and boil the mixture until it reaches the firm-ball stage, 246 to 248 degrees F.
With the stand mixer on low, slowly add the sugar syrup to the beaten egg whites, aiming it away from the whisk. Increase the mixer speed to high and beat until the mixture reaches room temperature (you can test this by placing your hand on the bottom of the mixing bowl) and is quite shiny and airy, 5 to 7 minutes. Add the vanilla and whisk for 1 minute more.
Refrigerate the clean bowl of the stand mixer and the whisk attachment (or a medium metal bowl and beaters from a hand mixer) until quite cold, about 15 minutes.
Once chilled, remove the bowl and whisk from the refrigerator, add the cream, and whip it on medium speed until just thickened.
Increase the speed to medium-high and whip the cream until it holds stiff peaks that stand upright when the whisk is raised (the stiffer the cream, the more support it will provide the crackers in your cake).
Gently fold the marshmallow cream into the whipped cream, being mindful not to deflate the cream; it’s okay to leave fluffy morsels of marshmallow throughout. Use it immediately.
To finish, lightly coat the sides of your springform pan with cooking spray, and line the sides of the pan with a 3-by-29-inch strip of parchment paper. Using a small offset spatula or the back of a spoon, spread a generous layer of the whipped cream on the bottom of the pan.
Cover as much of the whipped cream as possible with a layer of the Graham crackers, filling any gaps with broken crackers. The pieces should touch. The goal is a solid layer of Graham crackers.
Generously spread some of the pudding over the crackers.
Continue layering in this order (whipped cream, graham crackers, pudding, Graham crackers) until you run out or reach the top of the pan. Spread the top of the cake with a final layer of whipped cream and gently cover it with plastic wrap. Refrigerate for 24 hours.
Peel the plastic wrap from the cake and run a paring knife between the paper and the pan. Open the clamp, remove the pan sides, and gently peel back the parchment paper. Transfer the cake, still on the pan bottom, to a serving platter. Sprinkle crushed Graham crackers or grated chocolate on top of the cake. Using a knife, slice into wedges and serve.