Make ahead: Bake the casserole as instructed until the rice is tender, about 45 minutes. Stir in the broccoli and top with the cheese, then cool, cover, and freeze for up to 1 month. Thaw overnight in the refrigerator. Reheat, covered, in the oven at 350ºF until heated through, 30 to 45 minutes.
Storage: Refrigerate leftovers in an airtight container for up to 4 days.
