Hands On: 10 minutes Total: 25 minutes Cook pasta according to package directions; drain and keep warm. Spray large stockpot with cooking spray while pasta is cooking. Add chicken and onions; cook over medium heat 5 minutes, or until chicken chunks are no longer pink in centers, stirring frequently. Add tomatoes and soup; mix well. Cook until heated through, stirring occasionally. Drain pasta. Add to stockpot; mix well. Gently stir in spinach. Reduce heat to medium-low; cover stockpot with lid. Cook 3 minutes, or until spinach is wilted, stirring occasionally. Sprinkle with Parmesan cheese, if desired.