Pierce the eggplants with a sharp fork in two or three places (to keep them from exploding) and place them as high as you can on a V-rack roaster. Set over a medium-low gas flame or over hot coals and grill, turning about three times, 15 minutes to a side, or until completely soft and the skin is black and blistery, about 45 minutes total. The longer and slower the grilling, the creamier the eggplant will be. When the eggplants collapse, remove from the grill and let cool slightly. Remove the black parched skin, then squeeze gently to remove any juices. Discard the juices, and crush the pulp to a puree with a fork.