Double Chocolate Torte with Mascarpone Mousse and Wild Berry Sauce

To make the chocolate torte: Preheat the oven to 350 F. Line a 13-by-17-inch sided baking pan with parchment paper or waxed paper. In a large bowl, beat the egg yolks until they are pale yellow and thickened so that a slowly dissolving ribbon is formed on the surface of the yolks when the beater or whisk is lifted. In a double boiler over simmering water, melt the butter and chocolate together. Stir until smooth, then blend the chocolate mixture into the egg mixture.

In a large bowl, beat the egg whites until stiff, glossy peaks form, then fold them into the chocolate mixture. Spread the batter in the prepared pan and bake for about 30 minutes, or until a toothpick inserted in the center comes out clean. Let cool for 10 minutes, then invert and unmold onto a sheet of parchment paper or waxed paper. Scrape the top of the cake to remove the crust. Set aside.

To make the white chocolate mousse: Line a 6-cup semi-circular terrine, no deeper than two inches, with plastic wrap. (The terrine will make a “log” with one flat side.) In the top of a double boiler over simmering water, melt the chocolate and sugar, stirring to dissolve the sugar. Place the water in a cup and sprinkle the gelatin over it. Let it dissolve for about 3 minutes. Add the gelatin mixture to the chocolate and stir until smooth. Let cool slightly.

In a deep bowl, whip the cream until stiff peaks form, then fold in the pistachios. Fold the chocolate mixture into the whipped cream. Pour the mousse into the prepared terrine. Cover and freeze overnight, or at least 4 to 5 hours.

To make the mascarpone mousse: In a large bowl, whisk the cheese and sugar together until the sugar is dissolved. In a deep bowl, whip the heavy cream until stiff peaks form, then fold into the mascarpone mixture. Place in a pastry bag with a plain tip and refrigerate until needed.

To make the oil rigs and spouts: Draw four equal sides of an oil rig on paper set on a work surface. Cover each with an acetone plastic sheet.

Finely chop 1 cup of the chocolate and set aside. In the top of a double boiler over simmering water, melt the remaining chocolate and heat to 110 F. Remove from the heat and let cool slightly, then stir in the reserved chocolate and stir until the chocolate reaches 90 F. Hold the chocolate at that temperature, using a warm water bath (do not let any water — ANY water — get into the chocolate or it will seize) or a heating pad, as you work. The chocolate is now tempered.

Put some chocolate in a pastry bag fitted with a flat tip and draw the outline of the oil rig on the plastic. Let cool to harden. Make 48 to 64 oil rig sides. Make 12 to 16 spouts, drawing them free-hand with the chocolate. Refill the pastry bag as needed with warm chocolate. Save some of the melted chocolate for “glue.”

To assemble the rigs, place two sides at right angles, long edges together, and pipe a little melted chocolate along the seam; hold in place until cooled and firm. Repeat until all the pieces are in sets of two, then begin fastening two sets of two together to form four-sided rigs, using the same technique. Set the rigs and spouts aside.

To make the sauce: In a medium saucepan, combine 3 cups of the water and the sugar and bring to a boil over medium heat. In a small bowl, dissolve the cornstarch in the remaining water and add the rum. Whisk the cornstarch mixture into the boiling sugar syrup. Add the cocoa and stir until the mixture is thickened.

Meanwhile, in a double boiler over simmering water, melt the chocolate. Remove the rum mixture from the heat and stir in the melted chocolate. Strain the berries through a fine-meshed sieve, pushing them through with the back of a spoon. Add the berry puree to the chocolate mixture. Let cool, then strain again through a fine-meshed sieve.

To make the ganache: In a double boiler over simmering water, melt the chocolate with the cream, whisking gently to a smooth consistency. Let cool slightly to a pourable consistency.

To assemble the cake roll: Remove the white chocolate terrine from the freezer and unmold onto parchment paper or waxed paper. Remove the plastic wrap. Cut the cake to the proper length to encircle the terrine. Place the terrine on one edge of the cake and, with the aid of the parchment or waxed paper, roll the cake around the terrine to encase it, placing the seam on the flat side of the terrine. Trim the ends of the cake flush with the terrine. Place the cake roll flat-side down on a wire rack set over a sheet pan and coat the top and sides with ganache. Return the cake to the freezer to firm.

To serve: Remove the cake roll from the freezer and cut into 3/4-inch-thick slices. Place one slice on each dessert plate and stand an oil rig by the flat end. Fill the oil rigs with mascarpone mousse, piping it in from the top. Place the fresh berries around the edges of the plates. Ladle sauce down the sides of the rigs and around the plates over the berries. Garnish the cake rolls with mint sprigs. Stand a chocolate spout in the top of each oil rig in the mousse.