Triple Layer Chocolate Mousse Cake Americas Test Kitchen Recipe 385

Steps:

• Line three 9-inch cake pans with foil, leaving about a 2-inch overhang on all sides. (See Cook's Note.)
• Add the cookies and sugar to the bowl of a food processor and pulse to fine crumbs. Drizzle in the butter and pulse until the crumbs are completely coated and moistened with the butter. Firmly press the crumb mixture into the bottom of one of the prepared pans; set aside.
• Add the dark chocolate pudding mix to a large bowl and whisk in 2 cups of the heavy cream. Continue whisking until light and fluffy, about 2 minutes. (It's fine if there are still a few granules in the mix; they will dissolve once set.) Pour the pudding mixture on top of the crumb crust and spread until even. Freeze until firm, about 2 hours.
• Meanwhile, clean out the bowl, add the chocolate pudding mix and whisk in 2 cups heavy cream. Continue whisking until light and fluffy, about 2 minutes. Pour into another prepared pan and freeze until firm, about 2 hours.
• Clean out the bowl again, then add the white chocolate pudding mix and whisk in the remaining 2 cups heavy cream. Continue whisking until light and fluffy, about 2 minutes. Pour into the third prepared pan and freeze until firm, about 2 hours.
• When all 3 layers are completely frozen, use the foil to lift out the cakes from the pans. Place the dark chocolate layer crumb-side down on a cake stand or large plate. Top with the chocolate layer and then with the white chocolate layer. Refrigerate until the layers are thawed and the cake is set, about 8 hours and up to overnight.
• Before serving, run a hot knife around the outside of the cake to smooth it and sprinkle the top with the chocolate shavings.

Steps:

• To make the bottom layer, butter the bottom and sides of a 9-inch springform pan. (I lined the bottom of the pan with a parchment round for easy removal later.) Center a rack in the oven and preheat to 325˚ F. Combine the butter, chocolate, and espresso powder in a large heatproof bowl set over simmering water. Stir occasionally until the mixture is smooth. Remove from the heat and let cool slightly, about 5 minutes. Whisk in the vanilla and egg yolks. Set aside. In a stand mixer fitted with the whisk attachment, beat the egg whites and salt on medium speed until foamy, about 30 seconds. Crumble half of the brown sugar into the mixing bowl with your fingers to remove any lumps. Beat until incorporated, about 15 seconds. Add the remaining brown sugar and continue to beat on high speed until stiff peaks form, about 1 minute more. Using a whisk, mix one-third of the beaten egg whites to the chocolate mixture to lighten it. Fold in the remaining egg whites gently with a rubber spatula until no streaks remain. Pour the batter into the prepared springform pan and smooth the top with a spatula. Bake until the cake has risen, is firm around the edges and the center has just set but is still soft (should spring back after pressing gently with a finger), about 14-18 minutes. Transfer the cake to a wire rack to cool completely, at least 1 hour. Do not remove the cake from the pan. (If not making the second layer right away, cover with plastic wrap and refrigerate until ready to proceed.) To make the second layer, whisk together the cocoa powder and hot water in a small bowl; set aside. Melt the chocolate in a heatproof bowl set over simmering water, stirring occasionally until smooth. Once melted, remove from the heat and let cool slightly, 2-5 minutes. In the clean bowl of a stand mixer fitted with the whisk attachment, whip the cream, sugar and salt on medium speed until the mixture begins to thicken, about 30 seconds. Increase the speed to high and whip until soft peaks form when the whisk is lifted, 30-60 seconds. Whisk in the cocoa powder mixture until smooth. Using a whisk, mix one-third of the whipped cream to the chocolate mixture to lighten it. Fold in the remaining whipped cream gently with a rubber spatula until no streaks remain. Pour the mousse into the springform pan over the cooled cake and tap gently on the counter 3 times to remove air bubbles. Gently smooth the top with a spatula. Wipe the inside edge of the pan to remove any drips. Refrigerate for at least 15 minutes while preparing the top layer. To make the top layer, sprinkle the gelatin over the water in a small bowl and let stand at least 5 minutes to soften. Place the white chocolate in a medium bowl. Bring ½ cup of the cream to a boil in a small saucepan. Remove the pan from the heat, add the gelatin mixture and stir until dissolved. Pour the hot cream mixture over the white chocolate and let stand about 1 minute. Whisk until the mixture is smooth. Cool to room temperature, about 5-8 minutes, stirring occasionally. In the clean bowl of a stand mixer fitted with the whisk attachment, whip the remaining 1 cup of cream at medium speed until it begins to thicken. Increase the speed to high and whip until soft peaks form when the whisk is lifted, 30-60 seconds. Using a whisk, mix one-third of the whipped cream to the white chocolate mixture to lighten it. Fold in the remaining whipped cream gently with a rubber spatula until no streaks remain. Spoon the white chocolate mousse into the pan over the middle layer. Smooth the top with an offset spatula. Return the cake to the refrigerator and chill until set, at least 2½ hours. (Note: Do NOT cover your pan with plastic wrap unless you are completely sure you can do so without it touching the top of your cake during placement or removal. If it does touch the cake, it will smudge the perfectly pristine top, forcing you to make an excessive amount of chocolate curls. I speak from experience.)