Preheat the oven to 400°F (200°C). Coat a shallow 3-quart (3-L) casserole with cooking spray.
Cut the tomatoes into 4 slices each and overlap in the casserole to cover the bottom of the dish.
In a small bowl, mix the breadcrumbs, green onions, basil, parsley, garlic, thyme and salt and sprinkle the mixture evenly over the tomatoes. Drizzle with the balsamic vinegar and sprinkle with the cheese. Drizzle with olive oil.
Bake for 15 to 20 minutes, until the crumbs are crisp. Serve warm. Serves 6.