Preheat oven to 450F
Prick holes and rub oil on skin of eggplants and set on cookie sheet that has been lined with foil, shiny side down. Place in preheated oven and roast for approximately 1 hour or until eggplants collapse on themselves.
Take eggplants out of the oven and carefully open them to release steam and to allow them to cool enough to handle. Leave oven on for pita crisps.
Scoop insides of eggplants into a colander, removing as many seeds as possible. Allow to drain.
Add tahini, salt, pepper, garlic, 1/4 the parsley and 3/4 of the lemon juice to the food processor.
Squeeze excess moisture out of the eggplant flesh and then add to food processor.
Blend ingredients while pouring oil in to the working food processor. Stop, taste, adjust seasoning and resume blending and pouring oil until the consistency is to your liking, reserving a tablespoon or so of oil for finishing.
Place blended ingredients in a serving bowl.
Add sumac and cumin to remaining oil. Swirl into baba ganoush, letting the oil form puddles.
Sprinkle with fresh parsley leaves.