Cut the unpeeled eggplants into 1 inch cubes. Heat a large pot coated with nonstick cooking spray over medium-low-heat, and add the eggplant and onion, sautéing until lightly golden.
Add the celery, green pepper, parsley, pepper, and green olives to the pot, and stir gently but thoroughly. Simmer with cover for 30 minutes, stirring occasionally, and remove the lid. Then simmer about 10 minutes more, or until it is thick.
Cool and refrigerate. Serve chilled or at room temperature.