Ingredients:
12 oz of good quality dark chocolate, chopped
1-1/2 sticks of unsalted butter, cut into tablespoon pieces
1-1/2 teaspoons vanilla
1/4 teaspoon salt
3/4 cup sugar
5 large eggs, separated and at room temperature
1/4 cup all-purpose flour
1. Put rack in middle position and pre-heat oven to 350 degrees. Butter a 9-inch springform pan and line the bottom with parchment paper. Butter parchment paper.
2. Melt chocolate and butter in a metal bowl set over simmering water (or microwave in a glass bowl at 50 percent power for 4-5 minutes), stirring frequently. Then cool completely.
3. Whisk in vanilla, salt, 6 tablespoon sugar. Then whisk in egg yolks one at a time. Whisk in flour.
4. Beat the egg whites with a pinch of salt with electric mixer on medium-high speed until soft peaks form and then add 6 tablespoons of sugar, one at a time, and continue beating until stiff, glossy peaks form.
5. Whisk about 1/4 of whites into chocolate mixture to lighten it. Then fold in remaining whites gently. Pour batter into prepared pan and spread evenly.
6. Bake 35-40 minutes. A toothpick inserted in the center should come out with moist crumbs. Cool in pan for 10 minutes. Remove side of pan and cool completely. Invert cake onto rack and discard paper. Invert onto plate and serve.
