Stir boiling water into cornmeal in 3-quart bowl; continue stirring until smooth. Blend in margarine and egg yolks. Stir in remaining ingredients except egg whites.
Beat egg whites just until soft peaks form; fold into batter.
Pour into greased 2-quart casserole.
Bake until knife inserted near the center comes out clean, 45 to 50 minutes. 9 to 12 servings.