Gianduia Mousse Cake

Preparation

1. Step 1

   Preheat the oven to 350°F and butter a 10-inch spring-form pan. Wrap the bottom and side of the pan with a large piece of heavy-duty foil to waterproof.

   Step 2

   Chop the chocolates into small pieces and melt in a double boiler or a metal bowl set over a saucepan of barely simmering water, stirring until smooth. Remove the top of the double boiler or bowl from the heat and stir in the Nutella and hazelnut butter until combined well.

   Step 3

   In a large bowl of a standing electric mixer or in a large bowl with a handheld mixer, beat the eggs until frothy, about 1 minute. Gradually add the sugar, beating the mixture at high speed until thick and pale and until it holds a slowly dissolving ribbon when the beaters are lifted, about 4 minutes if using a standing mixer and about 8 minutes if using a handheld mixer. Pour the chocolate mixture into the egg mixture and stir until combined well. In a chilled bowl, beat the cream until it holds soft peaks and fold into the batter gently but thoroughly.

   Step 4

   Pour the batter into the spring-form pan and put springform pan in a larger roasting pan. Add enough hot water to the roasting pan to reach halfway up the side of the springform pan. Bake the cake in the middle of the oven 1 hour and 10 minutes. Turn off the oven and let the cake stand in the oven 40 minutes. Remove the springform pan from the water and cool cake in pan on a rack 30 minutes. Remove the side of the pan from cake. Let cake cool completely before serving. Serve with whipped cream.

2. do ahead

   Step 5

   The CAKE keeps, covered and chilled, 3 days.