Mix cream of mushroom soup,water,rice,onion powder and black pepper in shallow 2 qt (2 L) baking dish. Stir in vegetables (if frozen,thawed under running water).
Top with chicken breasts. Sprinkle chicken with additional pepper,if desired. Cover.
Bake at 375°F (190°C) until chicken is cooked through and rice is tender – about 45 minutes. Sprinkle cheese over chicken. Remove chicken and stir rice before serving.
