Ingredients

Melted unsalted butter for the pan
3 ounces semisweet chocolate, chopped
3 1/2 ounces unsweetened chocolate, chopped
1/3 cup water
9 tablespoons sugar
1 stick plus 1 tablespoon unsalted butter, melted
3 large eggs

Directions

Position a rack in middle of oven. Preheat oven to 325 F. Brush melted butter over bottom and sides of an 8-inch round cake pan that is 2 inches deep and line bottom with parchment paper. Brush paper with melted butter.

Bring water and 6 tablespoons of sugar to a boil, letting sugar dissolve before water boils. Remove from heat. Add semisweet and unsweetened chopped chocolates; stir until melted and smooth. Stir in melted butter to incorporate. Set aside to cool slightly.

Beat eggs and remaining 3 tablespoons of sugar with an electric mixer on high speed until thick and fluffy, about 3 minutes. In two additions, gently fold warm chocolate mixture into egg mixture. Pour batter into prepared pan, and put cake pan into a large baking pan. Put pans in oven and pour hot water in large baking pan to reach 1 inch up sides of cake pan.

Bake about 40 minutes until top looks firm and set. Cool cake in water bath for 15 minutes on a wire rack. (Water-bath baking consists of placing a container of food in a large, shallow pan of warm water.) Carefully remove cake from water bath and cool 1 hour more at room temperature. Cover with plastic wrap and refrigerate overnight. Run a small knife around sides of cake to loosen it from pan and unmold cake. Place a wire rack on cake and invert cake onto it. Discard paper liner. Place a plate on bottom of cake and invert cake so it is right side up.

Cut into slices and serve with lightly sweetened whipped cream, if desired. Makes 12 servings.

Nutritional information per serving (1 slice): 240 cal., 3 g pro., 16 g carbo., 20 g fat, 95 mg chol., 20 mg sodium.