Combine cornmeal, cheese, and milk in top of a double boiler. Place over boiling water, and cook, stirring constantly, until mixture reaches the consistency of mush. Remove from heat, and cool slightly. Beat egg yolks well. Stir in yolks, butter, sugar, and salt, mixing well.
Beat egg whites (at room temperature) until stiff peaks form; fold into cornmeal mixture. Spoon into a lightly greased 2- quart casserole. Bake at 375° for 30 minutes or until a knife inserted in center comes out clean.