Abstract: An energy conserving cooking or heating vessel assembly comprises an inner receptacle for receiving food or other materials to be cooked or heated and a cylindrical skirt or sleeve of larger diameter than the inner receptacle extending downwardly from a predetermined height on the side walls of the inner receptacle. The sleeve has an open lower end which is of larger diameter than a stove top recess for a gas burner or electric heating element, and the lower end is designed to rest on the flat surface of a stove top surrounding a burner or electric element recess to form an enclosed volume surrounding both the inner receptacle and the burner area below the inner receptacle. The skirt may be secured to the inner receptacle or may comprise a separate outer casing for receiving any conventional stove top vessel such as a saucepan or tea kettle.