In a skillet, cook beef and onion until meat is no longer pink and onion is tender; drain.

Sprinkle with salt and 1/4 teaspoon pepper; set aside.

In a large bowl, combine pasta, 3 cups of mozzarella cheese, cottage cheese, eggs, Parmesan cheese, parsley and remaining pepper; stir gently.

Pour into a greased 13 in. X 9 in. X 2 in. or shallow 3 qt. baking dish.

Top with the beef mixture and spaghetti sauce (dish will be full).

Cover and bake at 350°F for 45 minutes.

Sprinkle with remaining mozzarella.

Bake, uncovered, 15 minutes linger or until the cheese us melted and bubbly.

Let stand 19 minutes before serving.