Triple Chocolate Mousse Cake~

Adapted from Cook's Illustrated


For the bottom layer:

6 tablespoons butter, cut into pieces (plus extra for greasing the pan)

7 ounces semisweet chocolate, finely chopped

1/2 teaspoon instant espresso powder

1 1/2 teaspoons vanilla

4  eggs, separated

Pinch of salt

1/3 cup brown sugar


For the middle layer:

2 tablespoons Dutch processed cocoa powder

5 tablespoons. hot water

7 ounces semisweet chocolate, finely chopped

1½ cups heavy cream

1 tablespoon granulated sugar

Pinch of salt


For the top layer:

¾ teaspoon powdered gelatin

1 tablespoons water

6 ounces white chocolate, finely chopped

1½ cups heavy cream


For garnish:

Chocolate curls


To make the bottom layer, butter the bottom and sides of a high sided, 8-inch springform pan with 4 inch sides (9 inch diameter is OK, too). Center a rack in the oven and preheat to 325˚.  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 vanilla and egg yolks into chocolate.  Set aside.


With stand or hand mixer, 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, then add the remaining brown sugar and continue to beat on high speed until stiff peaks form.  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 completely incorporated.  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 23 minutes (14-18 minutes if using 9 inch pan).  Transfer the cake to a wire rack to cool completely, at least 1 hour.  Cake will fall. Do not remove the cake from the pan. 


To make the second layer, whisk together the cocoa powder and hot water in a small bowl; set aside.  Melt the chocolate gently in microwave, stirring occasionally until smooth.  Once melted, remove from the heat and let cool slightly, 2-5 minutes.


Whip the cream, sugar and salt on medium speed until the mixture begins to thicken, then increase the speed to high and whip until soft peaks form.  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 completely incorporated.  Pour the mousse into the springform pan over the cooled cake and tap gently on the counter 3 times to remove air bubbles.  Carefully smooth the top with a spatula.  Wipe down the inside edge of the pan to remove any chocolate.  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.  In a large Pyrex measuring cup, microwave 1/2 cup of the cream till it starts to boil.   Add the gelatin mixture to the cream 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. 


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.  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 well incorporated.  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.


To serve garnish with chocolate curls or cocoa powder.

Comments