1. Cook spaghetti according to package. Drain.
2. White the noodles cook, cook beef and onion in a skillet. When all the meat is browned, drain any extra grease. Stir in sauce and salt. Set aside.
3. Add eggs, Parmesan cheese, and butter to the drained noodles. Toss to coat.
4. Place half the spaghetti mix in a greased 9x13 pan. Top with half the cottage cheese, meat, and mozzarella cheese. Repeat layers.
5. Cover and bake at 350 for 40 minutes. Remove cover and bake another 20 minutes (until the cheese is melted).
*You can also place everything into a pan, cover, and freeze before you bake the noodle dish. Thaw over night and then follow baking directions.