Ingredients

Makes 6 Servings

　　9 ounces fine-quality bittersweet chocolate (not unsweetened), chopped

　　1 stick (1/2 cup) unsalted butter, cut into pieces

　　3/4 cup sugar

　　5 large eggs, separated

　　3 tablespoons all-purpose flour

　　2 tablespoons unsweetened cocoa powder

　　1 teaspoon vanilla

　　1/4 teaspoon salt

　　

Accompaniments:

coffee ice cream

　　Butterscotch Sauce

　　whipped cream if desired

　　

Step 1

Preheat oven to 350° F. Butter and flour a 9-inch square baking pan, knocking out excess flour.

　　

Step 2

In a metal bowl set over a saucepan of barely simmering water melt chocolate and butter, stirring occasionally, until smooth. Remove bowl from heat and whisk 1/2 cup sugar into chocolate mixture. Add yolks 1 at a time, whisking well after each addition, and whisk in flour, cocoa powder, vanilla, and salt.

　　

Step 3

In a bowl beat whites until they hold soft peaks and gradually add remaining 1/4 cup sugar, beating until whites just hold stiff peaks. Stir one fourth whites into chocolate mixture to lighten and fold in remaining whites gently but thoroughly.

　　

Step 4

Pour batter into baking pan, spreading evenly, and bake in middle of oven 40 to 45 minutes, or until a tester comes out with moist crumbs adhering. Cool cake in pan on a rack. (Cake will sink as it cools and top crust will crack.) Cake may be made 1 day ahead and kept, covered, at room temperature.

　　

Step 5

Cut cake into 9 squares (crust will shatter) and serve with ice cream, sauce, and whipped cream.