Pour the oil into a small saucepan, add the garlic and cook over a very low heat for 7 minutes or until the garlic starts to turn golden (if it turns black, you’ll need to start again). Remove from the heat and add the chilli.
Meanwhile, cook the pasta in a large saucepan of salted boiling water according to the pack instructions until al dente.
Drain the pasta, reserving a little of the cooking water. Whisk 2 tablespoons of the cooking water into the garlic and chilli oil to make a smooth sauce, then season and toss through the pasta, adding a little more water if needed.
Spoon on to serving plates and serve sprinkled with basil leaves.