Preheat oven to 375.
Pat chicken dry and place in a greased 9x13 pan.
Add sliced cheese on top of chicken breasts.
In a bowl mix mayonnaise, sour cream, ½ cup Parmesan cheese, salt, pepper and garlic powder. Spread this over chicken and sprinkle with remaining Parmesan cheese.
Bake for 1 hour. Serve over rice if desired or serve alone.
