Mix together cooked rice, chicken, cream of chicken soup, sour cream, softened cream cheese, Rotel, chili powder, red onion, black beans, and 1 1/4 cups cheddar cheese.
Pour into greased 9x13 baking dish or two smaller dishes.
Bake at 325 for 20-25 minutes.
Sprinkle additional 3/4 cups cheddar cheese over casserole.