Heat oven to 400°F. Spray 15x10x1-inch baking pan with nonstick cooking spray. Place 1 chicken breast half in each corner of sprayed pan. Place potatoes, bell pepper and onion in center of pan. Pour melted margarine over chicken and vegetables; sprinkle evenly with cheese, garlic powder and paprika.
Bake at 400°F. for 30 to 35 minutes or until chicken is fork tender and juices run clear, stirring vegetables once halfway through cooking.