Heat soup, stirring constantly.
Remove from heat and set aside.
Beat egg yolks until thick and stir into slightly cooled soup.
Beat egg whites until stiff; fold soup mixture into egg whites.
Pour into a 21/2-qt.casserole and bake 35 minutes at 325Â° F. and 10 minutes more at 350Â° F.
To serve: spoon cooked vegetables in onion sauce over each souffle serving.