Grease a casserole and line with cubed pineapple, drain. Flake 2 c. cooked fish mixed with 3/8 c. of cream; salt and pepper to taste; add to casserole. Beat together 1 c. mashed potatoes, 1 beaten egg, 2 tbsp. milk and a dash of paprika. Spoon over fish mixture. Bake in moderate oven until hot and brown. Remove from oven and top immediately with grated cheese.