Potatoes Au Gratin
["1/2 c. butter", "1 tsp. mustard", "1 tsp. salt", "6 medium potatoes", "1/4 c. milk", "1 tsp. pepper", "1/4 lb. cheese"]
["Boil and grate potatoes.", "Add mustard, salt, pepper, milk and cheese.", "Place grated potatoes in casserole and pour hot cheese over all.", "Bake at 350\u00b0 for 45 minutes."]
["butter", "mustard", "salt", "potatoes", "milk", "pepper", "cheese"]