Preheat the oven to 350°. Toss the tomatoes with the olive oil and thyme; season with salt and pepper. Spread the tomatoes, cut side down, on a rimmed baking sheet. Roast for 35 minutes. Pull off the tomato skins. Turn the tomatoes cut side up, top with the garlic and roast for 35 minutes longer, or until slightly dried and the garlic is golden. Let the tomatoes cool, then blot dry with paper towels. Leave the oven on.