SERVES 12 TO 16
This recipe requires a springform pan at least 3 inches high for all three layers to fit. It is imperative that each layer is made in sequential order. Cool the base completely before topping with the middle layer. We recommend Ghirardelli Bittersweet Chocolate for the base and middle layers; our other recommended brand of chocolate, Callebaut Intense Dark Chocolate, may be used but will produce drier, slightly less sweet results. Our preferred brand of white chocolate is Guittard Choc-Au-Lait White Chips. For best results, chill the mixer bowl before whipping the heavy cream. For neater slices, clean the knife thoroughly between slices.
BASE LAYER |
|
6 |
tablespoons (¾ stick) unsalted butter, cut into 6 pieces |
7 |
ounces bittersweet chocolate, chopped fine (see note) |
¾ |
teaspoon instant espresso powder |
4 |
large eggs, at room temperature and separated |
1½ |
teaspoons vanilla extract |
Pinch table salt |
|
⅓ |
cup packed (2⅓ ounces) light brown sugar, crumbled with fingers to remove lumps |
MIDDLE LAYER |
|
5 |
tablespoons hot water |
2 |
tablespoons cocoa powder, preferably Dutch-processed |
7 |
ounces bittersweet chocolate, chopped fine (see note) |
1½ |
cups heavy cream, chilled |
1 |
tablespoon granulated sugar |
⅛ |
teaspoon table salt |
TOP LAYER |
|
¾ |
teaspoon powdered gelatin |
1 |
tablespoon water |
6 |
ounces white chocolate, chopped fine (see note) |
1½ |
cups heavy cream, chilled |
Shaved chocolate or cocoa powder, for serving (optional) |
|
1. FOR THE BASE LAYER: Adjust an oven rack to the middle position and heat the oven to 325 degrees. Grease the bottom and sides of a 9-inch-wide by 3-inch-high round springform pan. Melt the butter, chocolate, and espresso powder in a large heatproof bowl set over a saucepan filled with 1 inch of barely simmering water, stirring occasionally until smooth. Remove from the heat and cool the mixture slightly, about 5 minutes. Whisk in the egg yolks and vanilla; set aside.
2. In a stand mixer fitted with the whisk attachment, beat the egg whites and salt at medium speed until frothy, about 30 seconds. Add half of the brown sugar and beat until combined, about 15 seconds. Add the remaining brown sugar and beat at high speed until soft peaks form when the whisk is lifted, about 1 minute longer, scraping down the sides of the bowl halfway through. Using a whisk, fold one-third of the beaten egg whites into the chocolate mixture to lighten. Using a rubber spatula, fold in the remaining egg whites until no white streaks remain. Carefully transfer the batter to the prepared pan, gently smoothing the top with a spatula.
3. Bake until the cake has risen, is firm around the edges, and the center has just set but is still soft (the center of the cake will spring back after pressing gently with a finger), 13 to 18 minutes. Transfer the cake to a wire rack to cool completely, about 1 hour. (The cake will collapse as it cools.) Do not remove the cake from the pan.
4. FOR THE MIDDLE LAYER: Combine the hot water and cocoa powder in a small bowl; set aside. Melt the chocolate in a large heatproof bowl set over a saucepan filled with 1 inch of barely simmering water, stirring occasionally until smooth. Remove from the heat and cool slightly, 2 to 5 minutes.
5. In the clean bowl of a stand mixer fitted with the whisk attachment, whip the heavy cream, sugar, and salt at medium speed until it begins to thicken, about 30 seconds. Increase the speed to high and whip until soft peaks form when the whisk is lifted, 15 to 60 seconds. Whisk the cocoa powder mixture into the melted chocolate until smooth. Using a whisk, fold one-third of the whipped cream mixture into the chocolate mixture to lighten. Using a rubber spatula, fold in the remaining whipped cream mixture until no white streaks remain. Spoon the mousse into the springform pan over the cooled cake and lightly tap the pan against the countertop two or three times to settle the mousse; gently smooth the top with a spatula. Wipe the inside edge of the pan with a damp cloth to remove any drips. Refrigerate the cake for at least 15 minutes while preparing the top layer.
6. FOR THE TOP LAYER: In a small bowl, sprinkle the gelatin over the water; let stand for at least 5 minutes. Place the white chocolate in a medium bowl. Bring ½ cup of the cream to a simmer in a small saucepan over medium-high heat. Remove from the heat; add the gelatin mixture and stir until fully dissolved. Pour the cream mixture over the white chocolate and whisk until the chocolate is melted and the mixture is smooth, about 30 seconds. Cool to room temperature, stirring occasionally, 5 to 8 minutes (the mixture will thicken slightly).
7. In the bowl of a stand mixer fitted with the whisk attachment, whip the remaining 1 cup cream at medium speed until it begins to thicken, about 30 seconds. Increase the speed to high and whip until soft peaks form when the whisk is lifted, 15 to 60 seconds. Using a whisk, fold one-third of the whipped cream into the white chocolate mixture to lighten. Using a rubber spatula, fold the remaining whipped cream into the white chocolate mixture until no white streaks remain. Spoon the white chocolate mousse into the pan over the bittersweet chocolate mousse layer. Smooth the top with a spatula. Return the cake to the refrigerator and chill until set, at least 2½ hours.
8. TO SERVE: Garnish the top of the cake with chocolate curls or dust with cocoa (if using). Run a thin knife between the cake and sides of the springform pan; remove the sides of the pan. Run the cleaned knife along the outside of the cake to smooth the sides. Serve.