Preheat oven to 375°.
In large skillet, brown meat and onion until no longer pink; drain.
Stir in spaghetti sauce with meat, heat to boiling. Reduce heat to low, simmer 5 minutes.
Meanwhile, cook pasta according to package directions for 7 minutes, drain.
In large bowl, stir together ricotta or cottage cheese, egg, parsley, pepper and salt.
In 9x13 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, pasta and cheese. Spread remaining meat sauce over pasta. Sprinkle with Parmesan cheese, if desired.
Cover with foil. Bake 30 minutes.
Remove foil, bake 5 minutes or until hot and bubbly.