Flourless Chocolate Cake

Directions

1. Let egg whites stand at room temperature for 30 minutes. Preheat oven to 350°. In a heavy saucepan, melt butter, 1/4 cup sugar and chocolates over low heat, stirring constantly. Cool until mixture is lukewarm.
2. In a large bowl, beat egg yolks until thick and lemon-colored, about 3 minutes. Beat in vanilla. Gradually beat in chocolate mixture.
3. In a small bowl and with clean beaters, beat egg whites on medium speed until soft peaks form. Gradually add remaining sugar, 1 tablespoon at a time, beating on high speed until stiff peaks form. Stir a small amount of whites into chocolate mixture. Fold in remaining whites.
4. Pour into a greased 9-in. springform pan. Place on a baking sheet. Bake until cake is just set and jiggles slightly when tapped, or until toothpick inserted in the center comes out with a few moist crumbs, 28-30 minutes. Cool on a wire rack for 20 minutes.
5. Carefully run a knife around edge of pan to loosen; remove side of pan. Drizzle with chocolate ganache if desired.