I found this recipe on Epicurious.com and it was originally printed in Bon Appétit in January 1999. I've made this a few times and each time it just gets better.
Flourless Chocolate Cake
12 ounces bittersweet (not unsweetened) or semisweet chocolate, chopped (note: I used half bittersweet and half semisweet)
3/4 cup (1 1/2 sticks) unsalted butter, cut into pieces
6 large eggs, separated
12 tablespoons sugar, divided
2 teaspoons vanilla extract
1/2 cup whipping cream
1/2 cup dark corn syrup
9 ounces bittersweet (not unsweetened) or semisweet chocolate, chopped (note: Again, I used half bittersweet and half semisweet)
Preheat oven to 350°F. Butter 10-inch-diameter springform pan. Line bottom of pan with parchment paper or waxed paper; butter paper. Wrap outside of pan with foil. Stir chocolate and butter in heavy medium saucepan over low heat until melted and smooth. Remove from heat. Cool to lukewarm, stirring often.
Using electric mixer, beat egg yolks and 6 tablespoons sugar in large bowl until mixture is very thick and pale, about 3 minutes. Fold lukewarm chocolate mixture into yolk mixture, then fold in vanilla extract.
Using clean dry beaters, beat egg whites in another large bowl until soft peaks form. Gradually add remaining 6 tablespoons sugar, beating until medium-firm peaks form. Fold whites into chocolate mixture in 3 additions. Pour batter into prepared pan.
Bake cake until top is puffed and cracked and tester inserted into center comes out with some moist crumbs attached, about 50 minutes. Cool cake in pan on rack (cake will fall).
Gently press down crusty top to make evenly thick cake. Using small knife, cut around pan sides to loosen cake. Remove pan sides. Place a cardboard round atop cake. Invert cake onto cardboard round bottom. Peel off parchment paper.
Bring cream and corn syrup to simmer in medium saucepan. Remove from heat. Add chocolate and whisk until melted and smooth.
Place cake on rack set over waxed paper. Spread 1/2 cup glaze smoothly over top and sides of cake. Freeze until almost set, about 3 minutes. Spoon remaining glaze over cake; smooth sides and top. Place cake on platter. Chill until glaze is firm, about 1 hour. Serve at room temperature.