Preheat the oven to 350°F / 175°C.
Peel the eggplant, slice it lengthwise into ½-inch thicknesses, then cut these slices into ½-inch cubes.
In a large skillet over medium heat, heat 2 tablespoons (30 ml / 1 fl oz) of the oil.
Add half the eggplant in a single layer and fry, tossing regularly, until browned and tender.
Remove to a platter and repeat with 2 more tablespoons of oil and the remaining eggplant.
Add the last tablespoon of oil to the same skillet.
Sauté the onions and garlic for about 5 minutes, until the onions have softened and are fragrant.
Stir in the drained tomatoes and cook for 5 minutes to allow the flavors to meld.
Add the chickpeas and the cooked eggplant back to the skillet.
Season generously with salt and pepper, toss well, and cook for 5 more minutes.
Spoon the mixture into a medium baking dish and stir in the minced parsley. At this point, the dish can be chilled for up to 24 hours; just bring to room temperature before baking.
Bake for 20 minutes, or until the casserole is hot and bubbly throughout.
Serve immediately.
