PREHEAT oven to 300° F. Grease 9-inch springform pan.
COMBINE water and corn meal in small saucepan. Cook over medium heat, stirring occasionally, until mixture comes to a boil about 3 to 4 minutes. Reduce heat to low. Cover; cook for 5 to 7 minutes or until mixture is thickened. Remove from heat; let stand 2 minutes. Add butter, 6 ounces broken baking bars and vanilla extract; stir until melted. Cool completely.
COMBINE 1/4 cup sugar and egg yolks in small mixer bowl. Beat at medium speed for 3 to 4 minutes or until mixture is thick and lemon-colored. Stir in chocolate mixture.
BEAT egg whites in large mixer bowl at high speed until soft peaks form. Continue beating; gradually add 2 tablespoons sugar. Beat until glossy and stiff peaks form. (DO NOT OVER BEAT.) Gently stir in chocolate mixture. Pour mixture into prepared springform pan.
BAKE for 40 to 45 minutes or until cake is set in center. Cool completely in pan on wire rack. Remove side of pan. Serve with whipped cream. Sprinkle with chocolate shavings, if desired.