Cook pasta according to package directions. Meanwhile, in a large nonstick saucepan coated with cooking spray, saute chicken until no longer pink; set aside.
In the same pan, saute onion and green pepper until crisp-tender. Add the spaghetti sauce, spinach, mushrooms and olives. Bring to a boil. Reduce heat; simmer, uncovered, for 5 minutes. Drain pasta; add chicken and pasta to the pan. Sprinkle with 1 cup cheese and toss to coat.
Transfer to a 13x9-in. baking dish coated with cooking spray; sprinkle with remaining cheese. Cover and bake at 350° for 20-25 minutes or until cheese is melted.