Heat oven to 300° F.
Slice the tomatoes in half and squeeze out the seeds. Place the tomatoes, cut-side up, in a small baking dish and scatter on the garlic and thyme. Drizzle with the oil and sprinkle with 1/4 teaspoon salt and 1/4 teaspoon pepper.
Bake until the tomatoes are soft but still hold their shape, about 2 hours.