To roast the vegetables:
Preheat oven to 425.
Toss chickpeas in 2 tablespoons olive oil, salt, pepper, cumin. Spread in a single layer on a baking sheet.
On a separate baking sheet, place eggplants, cut side up, and brush both sides with another tablespoon of olive oil.
Place both chickpeas and eggplants in oven (chickpeas on top rack) and roast for 30-40 minutes, flipping eggplants half way through. Test to make sure eggplant is tender all the way through with a fork.

To make the sauce and serve:
Whisk together all ingredients minus water and parsley in a small bowl or blend in a food processor. Add water, one tablespoon at a time, until sauce loosens and becomes creamy.
Serve eggplants with sauce topped with chickpeas and garnished with parsley.