Meanwhile, sprinkle flour in 3-quart saucepan or Dutch oven. Gradually add broth, stirring with whisk until blended. Heat to boiling, stirring constantly; reduce heat to medium. Cook 5 minutes or until thickened. Add butter; stir with whisk until melted. Add Parmesan cheese, half-and-half, sherry, salt, pepper and 1/2 cup of the Cheddar cheese; stir until cheese is melted. Stir in broccoli, rice and chicken.