Preheat oven to 425 degrees.
Coat a 2-quart baking dish with nonstick spray.
Arrange tomato slices, overlapping in prepared dish.
Season with 1/4 teaspoon salt and sprinkle with vinegar.
In a small bowl, combine breadcrumbs, garlic, thyme, pepper and remaining salt.
Sprinkle crumb mixture over tomatoes.
Bake tomatoes for 30-35 minutes, or until they are tender and the breadcrumbs are crisp and golden.
Sprinkle Parmesan cheese on top. (Optional)