Abstract: Two square self-enclosing interchangeable food baskets can be used singly, or stacked shelf-style, or stacked with the upper basket inverted to form a single tall domed compartment. To generally confine the steam, a separate cover fits closely with the upper basket in either orientation, or with the single basket if only one is in use; the lower basket fits closely with a water tray, and the two baskets fit closely with each other. Each basket is a unitary plastic component, eliminating the severe cleaning problems, hot-surface and possible health hazards, and high cost of aluminum trays used in earlier self-enclosing baskets. The water tray too is plastic, eliminating the similar cleaning problems, hazards, and high cost of cast-aluminum water trays in an earlier extendable self-enclosing system. A die-cast heater is mounted in a central orifice of the water tray, and surrounded by a central well formed in the tray.