Preheat the grill or broiler.
In a 10 to 12-inch saute pan, heat the oil until smoking. Add the onions, and cook until lightly browned or softened, about 6 to 8 minutes. Add the garlic and cook until soft, about 2 minutes. Add eggplant and cook, stirring regularly, until they turn golden brown and soft, resembling mushrooms, about 10 minutes. Remove the mixture from heat and season with salt and pepper. Allow the mixture to cool. Add the parsley and mix well to combine.
Grill or toast the bread until golden brown. Place each slice on a serving plate or in a shallow bowl. Divide the eggplant mixture over the bread and serve with shards of cheese and black pepper sprinkled over the top.
Recipe courtesy of Mario Batali