Cook's Note: Although traditional tians are baked in heavy ceramic dishes, you will have good results using a more common baking dish as long as it is shallow and has 2 1/2 to 3 quart capacity, such as a 12" x 2" x 7" Pyrex dish.
Combine all the vegetables, garlic, salt, pepper, and oil in a large bowl and toss well. (The vegetables can be prepared to this point up to 4 hours in advance.) Pack the mixture into a 2 1/2 or 3-quart shallow baking dish and flatten the top surface. Bake 45 minutes.
To make the fresh bread crumbs, tear up the bread and make crumbs out of it in a food processor or blender. Pour the crumbs into a bowl and drizzle with the oil. Rub the oil into the crumbs with your fingertips to moisten them evenly.
Remove the tian from the oven. Spread the crumbs all over the top. Return the tian to the oven and bake 15 minutes more, or until the topping is a rich golden color. Let sit 10 minutes before serving.