1. Heat oven to 375°F. Prepare pasta according to package directions; drain.
2. In large skillet, cook meat and onion until meat browns; drain. Stir in pasta sauce; heat to boiling. Reduce heat to low; simmer 5 minutes.
3. In large bowl, stir together ricotta cheese, egg, parsley, pepper and salt.
4. In 13 x 9 x 2-inch baking dish, spread 1 cup meat sauce; evenly layer one-half pasta over sauce. Spread ricotta mixture over pasta; sprinkle with 1 cup mozzarella cheese. Repeat layers of meat sauce and pasta. Spread remaining meat sauce over pasta, covering pasta completely; sprinkle with remaining mozzarella cheese. Sprinkle with Parmesan cheese, if desired; cover with foil. Bake 30 minutes. Remove foil; bake 5 minutes or until hot and bubbly.