The present invention is directed to a portable and microwaveable container into which a vessel may be inserted, and which assists in preserving or prolonging elevated temperatures of the contents of the vessel for an extended period of time. The container includes a receptacle area, or opening, into which the vessel is inserted. The container of the present invention may be heated, such as in a microwave oven, and once heated, a vessel containing a warmed food product, typically an elevated temperature liquid, may be inserted. The container of the present invention internally contains a microwaveable absorbing material which retains thermal energy. Once heated, the container passively improves the heat retention of the contents of the inserted vessel.