This was a specialty of my teacher chef Albert Kumin, who used to make it with a Grand Marnier flavored mousse at the Four Seasons restaurant in New York when he was the head pastry chef, about 50 years ago. I like to use this light chocolate mousse to fill it, and I’ve retained the orange liqueur as a flavoring.
Makes twenty-four 3 x 1 1/2-inch rectangles or twenty-four 2-inch squares
2 Baked Puff Pastry layers (see below)
2 cups heavy whipping cream
2 tablespoons orange liqueur, such as Grand Marnier or Cointreau
2 1/2 teaspoons (1 envelope) unflavored gelatin
1/4 cup cold tap water
1 cup egg whites (about 7 large egg whites)
1 cup sugar
12 ounces bittersweet (not unsweetened) chocolate, melted and cooled
Confectioner’s sugar and cocoa powder for finishing
One 9 x 13 x 2-inch pan, lined with aluminum foil
- First prepare the layers: Slide one of the baked puff pastry layers onto a cutting board and use a sharp serrated knife to trim it to the size of the inside of the 9 x 13-inch pan. (The easiest way to do this is to make a pattern with a piece of parchment paper.) Use a wide spatula to transfer one of the trimmed layers to the bottom of the prepared pan. Trim the other layer in the same manner and set it aside in a safe place.
- To start the mousse, whip the cream in a small bowl with the liqueur until it holds a soft peak. Cover and refrigerate.
- Sprinkle the gelatin in the water and set it aside to soften.
- Half-fill a medium saucepan with water and bring it to a full boil over medium heat. Combine the egg whites and sugar in the bowl of an electric mixer and whisk by hand just until smooth. Set the bowl over the pan of water and whisk gently, keeping the egg whites from setting in the bottom of the bowl, until the egg whites are hot (about 140 degrees) and the sugar is dissolved. Remove the bowl from the heat and whisk in the soaked gelatin.
- Place the bowl on the mixer with the whip attachment and whip the meringue on medium speed until the meringue has cooled to room temperature. Don’t overwhip or it will become grainy and ruin the texture of the mousse.
- While the meringue is whipping, remove the whipped cream from the refrigerator and whip again briefly if it has become watery. Once the meringue is cool (don’t cheat—warm meringue will melt the whipped cream and transform your mousse into a soup), quickly fold about 1/3 of the meringue into the chocolate, then quickly fold in the rest. Fold in the whipped cream.
- Scrape the mousse over the pastry layer in the prepared pan. Smooth the top and use a wide spatula to carefully transfer the second layer to the pan. Gently press with your fingertips to make the layer adhere to the mousse. Cover the pan with plastic wrap and refrigerate it for about 8 hours or overnight, to set the mousse. Keep the filled Napoleon chilled no longer than 4 hours before you intend to serve it.
- To unmold the pastry, grasp opposite ends of the foil lining the pan and lift it to a cutting board. This is best done by two people, with each one lifting a corner of the foil in each hand. Fold the foil down away from the sides of the mousse and run a long knife or spatula underneath, between the pastry and the foil, to loosen it. Carefully pull away the foil so that the pastry is on the cutting board.
- Use a long, sharp serrated knife to trim the sides even. Then gently saw through the top layer, cutting all the way straight through the filling and the bottom layer, cutting the pastry into 2- or 3-inch squares. Remember to wipe the knife clean between each cut.
- Sprinkle the tops of the pastries with confectioners’ sugar and then a tiny bit of cocoa powder.
BAKED PUFF PASTRY LAYERS
Makes one 10 x 15-inch baked puff pastry layer
About 12 ounces prepared all-butter puff pastry
Two 10 x 15-inch jellyroll pans, lined with parchment
- Lightly flour the work surface and place the dough on it. Flour the dough and use a rolling pin to press the dough in even strokes, close together and in the same direction (not back and forth). Turn the piece of dough 90 degrees and repeat.
- While you are rolling the dough, move it often and check to make sure there is always a light coating of flour on the work surface. Continue adding pinches of flour as needed under and on the dough.
- Roll the dough starting from the edge closest to you and roll away to the far end, without rolling over the edge. Roll back toward the beginning the same way. Turn the dough 90 degrees and repeat.
- While you are rolling, make sure that the corners remain straight and even and that the sides of the dough are also straight. Continue rolling and turning the dough until it is a little larger than 10 x 15 inches.
- Fold the dough in thirds and transfer it to one of the prepared pans. Cover the dough loosely with plastic wrap and refrigerate it for 1 hour or up to 24 hours.
- When you are ready to bake the layer, set a rack in the middle level of the oven and preheat to 350˚F.
- Remove the dough from the refrigerator and discard the plastic wrap. Use a fork to pierce all the way through the entire rectangle of dough at 1-inch intervals. Cover the dough with the piece of parchment paper from the other pan and place the other pan, right side up, on the paper.
- Bake the layer for 15 minutes. Then, using oven mitts, grasp the stack of pans firmly and turn the entire stack upside down and return it to the oven. Bake for 10 minutes.
- Turn the stack of pans right side up again and check the color of the layer. If it is an even deep golden color, remove and cool on a rack, leaving the layer between to pans to prevent it from warping as it cools. If it is not done, continue baking, checking the layer every 5 minutes to make sure it doesn’t burn.
- Use the layer for a finished pastry on the same day it is baked.
Storage: Keep the baked puff pastry layer between the two pans until you are ready to use it.
If you need two layers, use twice the amount of dough. Use 4 pans and bake them in the upper and lower thirds of the oven. At the point where you turn the layers over, switch the bottom pan to the upper rack and vice versa. If you only have 2 pans, bake as above, and the second layer can remain refrigerated until the first one is baked. Remember to let the pans cool completely before using them again.