1. Pre-heat the oven to 200°C (180°C fan-forced). Lightly grease a large baking dish.
  2. Bring a pot of salted boiling water to the boil and cook pasta as per packet directions. Drain.
  3. In a small frying pan, heat oil over a medium heat. Add onion and cook for 4 minutes, or until onion becomes translucent and aromatic.  Add the tomatoes, salt and pepper, cover and cook on a gentle heat for 20 minutes, or until the sauce has thickened.
  4. Add tuna and basil leaves, stirring until well combined. Add the cooked pasta, tossing until well coated.
  5. Place half the pasta into prepared baking dish, sprinkle over ½ cup Parmesan cheese to cover pasta. Add remaining pasta and sprinkle with remaining Parmesan cheese. Cover baking dish with foil and place in preheated oven for 25-30 minutes until cooked.  Remove foil for the last 5 minutes of cooking to allow the top of the pasta to become golden and crisp.