Crush graham crackers to make fine crumbs. Mix crumbs with brown sugar and chopped walnuts; set aside. Peel, core and slice apples. Arrange in buttered 8-inch baking dish in alternate layers with crumb mixture. Dot top with butter and pour lemon juice and water over all. Sprinkle with nutmeg. Cover and bake in slow oven at 350 degrees for about 30 minutes, until apples are cooked to a jelly. Serve hot or cold with cream or whipped cream.