Let egg whites stand at room temperature for 30 minutes.
Meanwhile, spray eight 6-ounce souffle dishes or custard cups with cooking spray. Sprinkle the bottom and side of dishes or cups with the 2 teaspoons granulated sugar.
In a medium saucepan, combine the 1/3 cup granulated sugar, the flour, cocoa powder, chocolate, coffee granules, and salt. Stir in evaporated milk. Cook and stir over medium heat until mixture is thickened and bubbly. Remove from heat. Stir in vanilla. Pour into a large bowl. Cover with plastic wrap. Cool completely.
In a large mixing bowl, beat the reserved egg whites and the cream of tartar with an electric mixer at high speed until soft peaks form (tips curl). Continue beating, adding the 1/3 cup granulated sugar, 1 tablespoon at a time, until stiff peaks form (tips stand straight).
Gently fold egg-white mixture into cooled chocolate mixture. Divide evenly among prepared souffle dishes. Cover and freeze for 2 hours or until firm.
Place souffle dishes with frozen mixture in a large baking pan. Place pan on an oven rack. Pour boiling water into pan around souffle dishes to a depth of 1 inch. Bake in a 350 degree F oven for 35 minutes or until puffed and a knife inserted near centers comes out clean. Sift with powdered sugar. Serve immediately. Makes 8 servings.