Place the tomatoes in a 9 x 13 ceramic dish and add the 1 1/2 T olive oil, thyme, 1 tsp. salt and 1/2 tsp. pepper and toss together. Spread this mixture evenly in the pan.
Place the garlic, parsley and 1/2 tsp salt in the bowl of a food processer fitted with a steel blade and process until the garlic is finely shopped. Add the bread cubvs and process until the bread is in crumbs. Add the 1/4 cup of olive oil and pulse a few times to blend. Sprinkle the crumbs evenly over the tomatoes.
Bake the gratin for 40-45 minutes until the crumbs are golden and the tomato juices are bubbling. Serve hot or warm.