Spray large skillet with nonstick cooking spray. Add chicken, cook over medium-high heat 5 to 7 minutes, or until light brown. Add water, rice, and contents of seasoning packets. Bring to a boil. Cover, reduce heat; simmer 20 minutes. Stir in pepper; sprinkle mushrooms over chicken. Continue cooking, covered, 5 to 8 minutes or until chicken juices run clear. Place cheese over chicken, remove from heat. Let stand covered 5 minutes or until cheese is melted.