Pre-heat the oven to 200°C(fan)/220°C/gas mark 7. Roast the butternut squash with the olive oil for 30-40 minutes until soft. Stir occasionally.
Add the roasted squash to the cheese sauce. Mix well. At this stage you can blend the vegetables into the sauce if you prefer.
Stir the sauce in to the cooked macaroni and transfer to an ovenproof dish.