Cut a slice off the stalk end of each tomato and set aside to use as lids. Scoop the pulp out of the tomatoes and chop. Transfer to a large bowl, taking care not to lose any of the tomato juices, and add the garlic, rice and basil. Season with salt and pepper and stir in 1 tablespoon of the oil. Cover and leave to stand at room temperature for 1 hour, for the rice to soak up all the juices.
Stuff the tomatoes with the rice mixture, then transfer to an oiled baking dish. Top with their reserved lids and drizzle with the remaining oil. Bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 35 minutes until the tomatoes are soft and the rice is cooked through. Serve warm or at room temperature.