Cook fettuccine to desired doneness as directed on package. Drain.
Meanwhile, spray large skillet with nonstick cooking spray. Heat over medium-high heat. Add chicken; cook and stir until no longer pink.
In small bowl, prepare sauce mix as directed on package. Add to chicken; bring to a boil, stirring constantly. Stir in mushrooms and peas; cook 5 minutes. Serve over fettuccine. If desired, sprinkle with Parmesan cheese.