1. Cook pasta according to package directions.
2. Sauté chicken in a non-stick pan over medium-high heat for 4-6 minutes or until lightly browned on both sides.
3. Add onions, mushrooms and summer squash, if desired, and cook an additional 6-8 minutes.
4. Stir in spaghetti sauce. Reduce heat to medium and cook till hot.
5. Serve chicken and sauce over pasta. Sprinkle with cheese