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 and pepper.
Stir in 1 cup of the spaghetti sauce; cool and set aside.
Reserve 1/2 cup of the ground beef mixture.
Combine remaining beef mixture with cheese in large bowl.
Arrange in greased 13x9" pan.
Combine remaining spaghetti sauce with reserved beef mixture in small bowl; blend well.
Cover with foil and bake in preheated 350 oven 20-30 minutes or until hot.