An adaptor (4) for adapting a domestic cooking apparatus (1) to supply power to a liquid heating vessel (5) having its own heating element is arranged to be received within a well (3) of the cooking apparatus (1). The heating vessel (5) is supported on the upper surface (12) of the adaptor (4). The adaptor has a first electrical connector (18) which releasably engages with the socket connector (20) in the well wall, which normally receives the heating element (2) of the cooking apparatus. A second electrical connector (22) electrically connected to the first connector means is arranged in the upper surface (12) for detachable engagement with the terminal pins (34,36,38) of the vessel (5).