Drain oysters. Melt butter and sauté celery. Add onions, parsley, spinach, anise seed, Worcestershire sauce, bread crumbs, salt, pepper and cayenne. Grease a shallow casserole. Arrange oysters in one layer only. Cover with Rockefeller mixture as thick as desired. Bake in 450ºF. oven for 30 minutes. Remove and sprinkle with grated cheese and a very thin layer of bread crumbs. Return to oven for 10 minutes until slightly brown.