Preheat the oven to 500˚F. Line a rimmed baking sheet with aluminum foil.
Poke the eggplants randomly all over with the tines of a fork and place on the prepared baking sheet. Roast, turning once, until the eggplants are soft, about 30 minutes. Remove from the oven and let cool.
Meanwhile, heat the olive oil in a medium skillet over medium-low heat. Add the onions and cook, stirring, until lightly golden, about 10 minutes. Remove from the heat and set aside.
Peel the eggplants and put the flesh into the bowl of a food processor. Add 1/4 cup of the lemon juice, 2 teaspoons extra virgin olive oil, the garlic, tahini, salt, black pepper, and cayenne. Process until smooth. Transfer the mixture to a serving bowl and fold in the onions. With the back of a spoon, make a shallow indentation in the middle of the dip. Drizzle in the remaining teaspoon extra virgin olive oil and 1/2 teaspoon lemon juice, sprinkle with the parsley, and serve with Pita Chips.
Makes about 2 1/4 cups