Preheat the oven to 375 degrees. Combine all the vegetables, garlic, and rosemary in a large mixing bowl. Sprinkle on the salt, pepper, and 1/3 cup olive oil and toss to coat thoroughly. (The vegetables may be prepared to this point up to 4 hours in advance.)
Drop the vegetables into a shallow 2 1/2 quart ovenproof casserole and press them down evenly. Bake 45 minutes.
To make the topping, break up the bread and make coarse crumbs in a food processor. Scrape them into a small bowl and drizzle on the 1 tablespoon olive oil. Use your fingers to rub the oil evenly into the crumbs.
Remove the tian from the oven. Sprinkle the crumbs all over the top. Return the dish to the oven and bake 15 more minutes, or until the vegetables are very tender. Let sit 10 minutes before serving.