Serve these tomatoes over grilled or toasted rustic bread; spread any oil remaining in the skillet over the bread before grilling.
Heat oven to 300 degrees. Arrange tomatoes, basil, and garlic in a large cast-iron skillet. Pour the olive oil over tomatoes; toss to coat.
Transfer skillet to oven. Roast until tomatoes are soft, melted, and skins start to pop, about 40 minutes. Remove from oven, and season with salt and pepper. Serve warm or at room temperature.