My coworker brought this in to the office for a birthday celebration. It was chocolaty decadence in its finest so I asked her for the recipe. It originally was in the November 1989 issue of the magazine Bon Appetit. I highly recommend it!
Flourless Chocolate Cake
10 tablespoons (1 1/4 sticks) unsalted butter
1/2 cup sugar
8 ounces semisweet chocolate, chopped
4 ounces bittersweet (not unsweetened) or semisweet chocolate, chopped
1 tablespoon brandy
4 large eggs, separated, room temperature
1 teaspoon vanilla extract
1/4 teaspoon salt
Preheat oven to 425 degrees. Butter 9-inch-diameter springform pan with 2 1/2-inch-high sides. Coat pan with sugar; tap out excess. melt 10 tablespoons butter with 1/4 cup sugar in heavy medium saucepan over low heat, stirring until sugar dissolves. Add both chocolate and stir until melted. Remove from heat. Mix in brandy.
Whisk yolks in medium bowl until thick and pale yellow, about 4 minutes. Whisk in warm chocolate mixture and vanilla (mixture will be very thick and may appear broken). Using electric mixer, beat whites with salt in large bowl until foamy. Gradually add remaining 1/4 cup sugar, 1 tablespoon at a time and beat until soft peaks form. Whisk 1/3 of whites into chocolate mixture. Gently fold in remaining whites.
Pour batter into prepared pan. Bake until top forms crust but center of cake remains moist and moves when pan is shaken, about 15 minutes (cake will appear undercooked). Let stand in pan overnight (cake will fall as it cools).
Run small sharp knif around cake pan sides to loosen, if necessary. Release pan sides from cake. Sift powdered sugar over. Cut into wedges.