Prepare noodles according to package directions making sure to drain, rinse with warm running water and drain again. Preheat oven to 375.
Brown ground beef with onion; drain. Combine beef mixture with 1/2 C cheese and remaining ingredients, except sauce; mix well. Fill prepared pasta.
Pour 1 cup sauce in bottom of 11x7 baking dish; arrange manicotti over sauce. Pour remaining sauce over manicotti. Cover with foil and bake at 350 for 30 minutes. Uncover, sprinkle 1 C shredded mozzarella over top, bake for 5 minutes until cheese melts and bubbles.