Preheat the oven to 200°C/gas mark 6. Bring a large pan of water to the boil, then add the pasta and cook for 6 minutes. Drain. Tip the cooked pasta back into the pan and stir through the pasta sauce, tuna, sweetcorn, chopped tomatoes and half the parsley.
Tip the mixture into a 1½-litre baking dish and sprinkle the cheese over the top. Cook for 30 minutes until golden and bubbling. Garnish with the remaining parsley just before serving.