Abstract: An imperforate, highly heat-absorbent pellet is enclosed between vertically-spaced upper and lower wall members which are sealed together only at their outer peripheries. A layer of thermal insulation is interposed between the pellet and the lower wall. The pellet is maintained in a centered position in the serving base primarily by a peripheral, upwardly-inclined, thin flange about the pellet which contacts an upwardly-inclined side portion of the upper wall. A raised center portion of the upper wall has a wall descending to a depressed ring just inwardly of the side portion; the pellet has a corresponding downward step contacting the descending wall and assisting in aligning the parts. The pellet and server base thereby are made rigid against deformation and rendered substantially non-burstable upon heating.