Mocha Mascarpone Icebox Cake

Ingredients

• For the cookie layers:
• 1 batch unbaked Tate's-style chocolate chip cookie dough
• For the filling:
• 16 ounces mascarpone, cold
• 16 ounces heavy cream, cold
• 3 ounces brown sugar
• 2 ounces bittersweet liqueur, such as crème de cacao or Kahlúa
• 1 ounce high-fat Dutch cocoa powder, sifted; see our recommended Dutch cocoas here
• 1 1/2 teaspoons instant espresso powder, plus more to taste
• 1/4 ounce vanilla extract, plus more to taste; see our recommended vanilla extracts here
• 1/4 teaspoon Diamond Crystal kosher salt, plus more to taste; for table salt, use about half as much by volume or the same weight
• To Serve:
• One 3-ounce chocolate bar
• 6 ounces heavy cream

Directions

1. For the Cookie Layers: Set a rack in the center of the oven and heat it to 350 degrees F (180 degrees C). Divide the unbaked cookie dough as directed in its recipe. Line a half-sheet pan with parchment, draw two 8-inch circles on the paper, then turn the parchment over so the markings are underneath. Set 7 pieces of dough inside each circle in a flower-like arrangement. Bake for about 20 minutes, until the dough has spread into the marked rounds and the cookies are thin, evenly golden, and browned from the edges through the centers. As soon as they come out of the oven, while the cookies are still pliable, use a knife to coax the edges back inside the circles, trimming where necessary; save those little pieces. Continue baking this way until you have a total of 5 cookie sheets. Bake any extra dough as separate cookies, or freeze it as instructed in the original dough recipe for another day.
2. For the Filling: Add the mascarpone to the stand mixer bowl along with the cream, brown sugar, liqueur, sifted Dutch cocoa, instant espresso powder, vanilla, and salt, and fit the mixer with the whisk. Start on low and mix until the ingredients look mostly combined, then raise the speed to medium and whip until the cream forms soft peaks. Taste it, ideally on one of the saved cookie trimmings, and adjust with more salt, espresso powder, or vanilla if needed. Turn the mixer back to medium and keep whipping until the mixture is firm, thick, and spreadable, more like frosting. Taste again with the reserved scraps, and add any extra salt, espresso powder, or other flavoring if you think it needs it.
3. To Assemble: You will need a nonreactive loose-bottom aluminum pan that measures 8- by 4-inch; Lloyd Pans' 8"x4" cheesecake pan is the style intended here. A nonreactive springform pan with different dimensions can work too, but you will need to make your own small adjustments as you build the cake.
4. Spoon about 6 ounces (170g) of the whipped filling into the loose-bottom pan, then use an offset spatula to coat the sides in a smooth layer. Set 1 baked cookie sheet into the base of the pan and press it lightly so it sits level. If it cracks, carry on. Spread about 7 1/4 ounces (205g) of filling over the cookie in an even layer. Continue layering the remaining cookie sheets and cream the same way, using all of the cream and leaving the final cookie uncovered. Cover with foil and refrigerate for at least 6 hours, but preferably no longer than 18 hours; after that, the bottom cookie layer may become too soft to move neatly.
5. To Serve: Right before serving, make chocolate curls by pulling a stick peeler along the long side of a chocolate bar, with wax paper or parchment underneath to catch the shavings. Milk chocolate behaves best at about 70 degrees F (21 degrees C); if it is colder, it may snap, and if it is warmer, it can feel sticky. You can shave dark chocolate the same way, though it usually cooperates better when it is a few degrees warmer, since it can still be brittle at 70 degrees F. Whip the heavy cream until it holds medium-soft peaks.
6. Set the cold icebox cake out briefly so the outer cream layer can loosen. At roughly 70 degrees F (21 degrees C), this should take about 5 minutes, and it will take less time when the room is warmer. In cooler weather, wrapping the pan for a moment in a kitchen towel dampened with hot tap water can help.
7. To unmold, set the pan on a large can of tomatoes or another object of similar size, tall enough to raise the cake at least 4 inches above the counter and broad enough to stay steady. Hold the sides of the pan with both hands and pull the outer ring down, letting it fall away from the base. Work an offset spatula or a wide, flat cookie spatula underneath the cake and wiggle gently to release it, then slide your hand under it and move it to a serving plate. Finish with the whipped cream and chocolate curls. Slice into wedges with a large chef's knife, washing the blade under hot running water between cuts. Serve immediately.
8. Serving and Storage Tips: How long this cake keeps well depends on the amount of time it spent chilling before serving and on the texture you prefer, since the cookies continue to soften and break down as they sit. Some people will like that very tender texture, while others may find it too soft. If you serve the cake soon after the recommended chill, the cookies will be more crisp and toothsome; that contrast may be just right for some, and a little too firm for others.