Cook cabbage in boiling water seasoned with salt and sugar for 4 minutes. Drain very well and put in a 2 quart flat casserole. Make a cream sauce with butter, flour and milk by melting butter in saucepan, stirring in flour and slowly adding milk. Cook until thickened over medium heat. Pour over cabbage; sprinkle with buttered cracker crumbs. Bake at 325 degrees for 45 minutes. Serves 4 to 6.