Boil a pot of water and cook ziti pasta according to package directions.
Meanwhile, saute ground beef along with frozen onion and peppers until beef is brown and vegetables are tender. Drain and return to pan.
Stir in tomato sauce, Italian seasonings, salt, and pepper. Simmer for 10 minutes.
In a small bowl, beat egg. Stir in ricotta cheese. Spray a 9 x 13 inch baking dish with non stick spray.
Spread half of meat sauce in bottom of dish. Top with half of ziti pasta, half of ricotta mixture, and half of shredded mozzarella. Repeat layers once more ending with mozzarella. Sprinkle additional Italian seasoning over mozzarella.
Cover with foil and bake at 350 degrees for 25 minutes or until hot and bubbly. Remove cover and allow casserole to rest 5 minutes before serving.