Special equipment: Blowtorch
For the chocolate porcini cookie crust: Preheat the oven to 375 degrees F. Cream together 3 ounces sugar with the butter in a mixing bowl until very light and well combined. Add the flour, cocoa powder, porcini powder and salt and mix just to combine. Spoon the dough in teaspoon-size chunks onto a silicone baking mat-lined pan. Bake until the dough starts to set, about 10 minutes.
Remove from the oven and use a clean, dry dishcloth to crumble the mixture. Return the crumbs to the oven, and continue to bake and then crumble in about 6-minute intervals until dry. Let the crumbs cool, and then pulse in a food processor or crush with a rolling pin to make fine crumbs. Reserve 1/2 cup of the crumbs. Combine the remainder of the crumbs with just enough of the melted butter to dampen and hold the crumbs loosely together. Press the cookie crust into the bottom and sides of a springform pan or the bottom of individual round molds. Bake the crust for about 8 minutes, just until set and dry.
For the candy cap pastry cream: Bring the milk, heavy cream and mushrooms to a boil in a saucepan over high heat. Remove from the heat and cover with plastic wrap. Let steep for about 30 minutes. Strain the mushrooms out of the milk and cream mixture and return the milk and cream mixture to the saucepan, and return to a boil.
Stir together the sugar and cornstarch in a bowl. Whisk in the yolks and the egg until smooth. Temper a small amount of the milk into the egg mixture and whisk until combined. Add the egg mixture into the saucepan and stir constantly. When the mixture begins to bubble, let it bubble for about 30 more seconds and then remove from the heat. Place in a bowl and cover with plastic wrap. Let it cool down in the refrigerator.
Once cooled, fill the crusts to the top and smooth out. Let set up in the refrigerator for about 4 hours. For the italian meringue: Combine the sugar with about 1/3 cup water in a small pot over low heat. Swirl the pot over the burner to dissolve the sugar completely. Do not stir. Increase the heat and boil the sugar until it has reached soft-ball stage (235 to 240 degrees F). Use a candy thermometer for accuracy. Wash down the inside wall of the pot with a wet pastry brush. This will help prevent sugar crystals from forming around the sides.
Meanwhile, whip the egg whites on low speed in the bowl of an electric mixer until foamy. Increase the speed to medium, and beat until soft peaks form.
With the mixer running, pour the hot sugar syrup in a thin stream over the fluffed egg whites. Beat until the egg whites are stiff and glossy. Pipe a "kiss" on top of the pie or smaller individual pies. Using a blowtorch, lightly torch the meringue and gently run around the ring. Pull the ring up from the bottom to remove from the icebox pie.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.