Cook spaghetti noodles according to package directions. While noodles are cooking in a large skillet brown ground beef with the onion until the beef is no longer pink. Drain.
Stir in spaghetti sauce and seasoning salt. Set aside.
In a large bowl mix egg, parmesan cheese and butter. Drain spaghetti noodles and toss with the egg mixture until they are coated thoroughly.
Place half of the spaghetti noodles in a greased 13 x 9-inch baking dish. Top with half of the cottage cheese, half of the meat sauce, and half of the mozzarella cheese.
Repeat layers cover and bake at 350 degrees for 40 minutes. After 40 minutes uncover and top with the remaining mozzarella cheese.
Return to the oven and bake for 20 minutes or until the cheese has melted.