Source: Gourmet - February 1998

9 ounces fine-quality bittersweet chocolate (not unsweetened)
7 ounces fine-quality milk chocolate
1 cup Nutella
3/4 cup unsweetened hazelnut butter
6 large eggs
1/2 cup superfine granulated sugar
1 cup well-chilled heavy cream
Accompaniment: whipped cream

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

Chop 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 top of double boiler or bowl from heat and stir in Nutella and hazelnut butter until combined well.

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

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

Serve cake with whipped cream. Cake keeps, covered and chilled, 3 days. Cake served at room temperature will have a texture reminiscent of mousse; chilled cake will be more fudge-like.

Makes 12 to 14 servings.