Combine cornmeal and boiling water in a large bowl; stir with a wire whisk until well blended. Add margarine, egg yolks, and next 5 ingredients, stirring until dry ingredients are moistened.
Beat egg whites at high speed of an electric mixer just until stiff peaks form. Gently fold egg white into cornmeal mixture. Coat an 11- x 7- x 1 1/2-inch baking dish with cooking spray. Pour batter into prepared dish. Bake at 375° for 28 to 30 minutes or until golden.