Fran’s Marquis au Chocolat

The Marquis, a perfectly smooth, dense loaf of chilled bittersweet mousse, is a classic French restaurant dessert. It cuts beautifully into very thin slices, can be made a day or two in advance, and there’s no baking involved. The most important moment making the Marquis is whipping the cream––it must be extremely loose to keep the texture lush. Serve with additional lightly whipped cream, Raspberry Sauce or Crème Anglaise, and fresh raspberries.

Serves 12 to 16

Ingredients

5 large eggs, separated
½ cup plus 2 tablespoons sugar
½ cup water
8 ounces bittersweet chocolate, finely chopped
4 ounces unsweetened chocolate, finely chopped
1 ½ sticks (12 tablespoons) unsalted butter, room temperature
1 cup heavy cream, chilled
dark chocolate curls for decorating

Directions

Line the long sides and bottom of an 8½-by-4½-inch loaf pan with a single sheet of parchment paper measuring 8 by 14 inches. Then cut a 16-by-4-inch sheet of parchment and line the bottom and short sides. There should be an excess of paper overhanging the pan in order to easily lift and remove the finished loaf.
In the top of a double boiler or heatproof bowl, whisk the egg yolks and ¼ cup sugar together until pale yellow and thick. A ribbon should fall back in the bowl when the whisk is lifted, and the sugar should begin to dissolve.
Stir in ¼ cup of water. Place over simmering water and cook, whisking vigorously, until the mixture is quite thick and foamy, 160°F.
Remove from the heat and add the finely chopped chocolates. Stir until melted. Continue stirring until cool to the touch. Stir in the softened butter. Set aside.
In a separate bowl, whisk the cream until soft peaks form. Chill in the refrigerator.
In a small heavy saucepan, combine the remaining sugar (¼ cup plus 2 tablespoons) with the remaining ¼ cup water. Cook over medium heat, stirring until the sugar is dissolved and the mixture is clear. Increase the heat to high and boil, without stirring, until it thickens and large bubbles form, about a minute.
Meanwhile, in the bowl of a mixer fitted with a clean whisk, begin whipping the egg whites on medium-high speed, increasing the speed until soft, glossy peaks form. With the mixer running, add the boiling sugar syrup in a slow, steady stream. Continue whipping until the peaks are stiff but not dry and the mixture feels tepid, about 90°F.
Lighten the cooled chocolate mixture by quickly folding in one-quarter of the beaten whites. Then gently fold in the remaining whites in 3 parts, trying not to overmix and lose the volume.
Repeat the folding process with the chilled whipped cream in 3 parts, gently folding until you can no longer see any streaks of white.
Evenly spread the mixture into the prepared pan, folding the excess parchment over the top. Cover with plastic wrap.
Place in the refrigerator or freezer to set, about 4 hours.
Remove from the refrigerator or freezer. If frozen, let sit about 10 minutes to warm. Holding the flaps of parchment paper with both hands, gently lift the loaf from the pan. Invert onto a serving plate. Remove the parchment.
Store the Marquis in the refrigerator. Serve chilled, cutting with a warm, dry knife. The flavors will get stronger as it warms up on the plate. Serve with lightly whipped cream.