Cook and drain manicotti shells. Cook beef in oil in large skillet over medium high heat until brown, stirring to separate meat; drain fat. Stir in onion powder, salt andpepper. Stir in 1 cup of the spaghetti sauce; cool and set aside. Reserve half cup of the ground beef mixture. Combine remaining beef mixture with cheese in large bowl. Stuff into manicotti. Arrange in greased 13x9 inch pan. Combine remaining spaghetti sauce with reserved beef mixture in small bowl; blend well. Pour over manicotti. Cover with foil. Bake in preheated 180ºC oven 20-30 minutes or until hot. Garnish as desired.