Tiramisu Icebox Cake

Line an 8×8-inch square baking pan with plastic wrap or parchment paper on all sides. In a stand mixer fitted with the whisk attachment, add the cream, confectioners’ sugar, and vanilla extract and beat on low speed until combined, so the cream doesn’t fly everywhere. Gradually increase the speed to high and beat until medium peaks form, about 2 minutes. Add the mascarpone and beat on low speed until smooth and combined, about 30 seconds.

In a shallow, wide bowl, combine the coffee, granulated sugar, and rum. Quickly dip the graham cracker sheets into the coffee mixture one at a time (otherwise they’ll get soggy and fall apart!), then layer them in a single layer in the bottom of the prepared pan (you may need to break apart a few graham cracker sheets to fully cover the bottom of the pan). Scoop 1 cup of the mascarpone whipped cream mixture on top of the graham crackers and use a silicone spatula to spread it evenly to the edges. Repeat this layering process of soaked graham crackers and 1 cup mascarpone whipped cream so you end up with 5 layers of graham crackers and 5 layers of mascarpone whipped cream, with the mascarpone whipped cream being the top layer.

Transfer the remaining mascarpone whipped cream to a piping bag fitted with a 1-inch round tip (if you don’t have a piping bag, place the filling in a large resealable plastic bag and cut off a corner with scissors). Pipe 1-inch circles of mascarpone whipped cream over the entire surface of the cake.

Place the pan, uncovered, in the fridge to chill for at least 4 hours and up to 2 days (if serving longer than 4 hours away, refrigerate the cake, uncovered, for 4 hours, then lightly cover it with plastic wrap). When you’re ready, take the cake out of the fridge, generously dust the top of the cake with cocoa powder, slice it, and serve.