Make the pasta as per the packet instructions (this usually takes 10 minutes). Drain well.
Spray a frying pan with low-calorie cooking spray, and set on a medium heat. Add the onion and fry for 8-10 minutes – until caramelised.
Preheat the oven to 200ºC.
Add the onion to the cooked pasta – along with the spreadable cheese and basil, and mix well. Season to taste.
Transfer the pasta to an ovenproof dish, sprinkle the cheese on top, and bake for about 15-20 minutes – until golden brown.