- 1 pound bittersweet chocolate, chopped into small pieces
- 1 stick unsalted butter*
- 9 large eggs, separated
- 3/4 cup granulated sugar, plus 1 tablespoon
- 2 cups heavy cream, cold
- Confectioners' sugar, for dusting
- Preheat the oven to 350 degrees F.
- Butter a 9-inch springform pan.
- Put the chocolate and butter into the top of a double boiler (or in a heatproof bowl) and heat over (but not touching) about 1 inch of simmering water until melted. Meanwhile, whisk the egg yolks with the sugar in a mixing bowl until light yellow in color. Whisk a little of the chocolate mixture into the egg yolk mixture to temper the eggs - this will keep the eggs from scrambling from the heat of the chocolate - then whisk in the rest of the chocolate mixture.
- Beat the egg whites in a mixing bowl until stiff peaks form and fold into the chocolate mixture. Pour into the prepared pan and bake until the cake is set, the top starts to crack and a toothpick inserted into the cake comes out with moist crumbs clinging to it, 20 to 25 minutes. Let stand 10 minutes, then remove sides of pan.
- While the cake is cooking, whip the cream until it becomes light and fluffy.
- Serve at room temperature dusted with confectioners' sugar and topped with whipped cream.