A microwave oven is disclosed which is especially useful for rapidly reconstituting frozen food products. The oven includes a microwave cavity having a bottom hatch which is movable between an open position at which food to be heated or cooked can be loaded onto the hatch from outside the oven, and a closed position whereat the food is disposed within the cavity for heating or cooking by electromagnetic energy. The hatch can be manually closed and, after a preset cooking time, automatically opened by gravity. Also disclosed is a heat shield assembly mounted for movement relative to the bottom of the cavity, so that when the hatch is in its open position and electric (IR) heat is provided to supplement microwave heating in the cavity, the assembly covers the bottom of the cavity to prevent heat from radiating below the cavity when the food is supported on or removed from the movable hatch. Accordingly, each batch of the food undergoes a uniform energy exposure, regardless of the time it may be left unattended below the cavity after the hatch is returned to its open position. The oven can be cycled rapidly to provide an adequate supply of food products when used in a retail establishment.
