Stir in the cheese, salt and plenty of black pepper and cook over a medium heat for 2–3 minutes, or until the cheese has melted, stirring occasionally. Using a hand-held stick blender, blend the squash and sweet potato mixture until smooth. Don’t overcook it as you will be cooking it further in the sauce. Meanwhile, bring a large saucepan of water to the boil (use your largest pan, or you may need to use two saucepans), then add the pasta and cook for 8–9 minutes, or until just tender. If you're baking rather than microwaving the dish, preheat the oven to 220C/200C Fan/Gas 7. Bring to the boil, then reduce the heat and simmer for 10 minutes, or until the vegetables are tender. Stir the butternut squash and sweet potatoes into the onions, then stir in the stock and milk.

Meanwhile, crumble the stock cubes into a large, heatproof jug, add the boiling water and stir well until dissolved. Add the oil and onions and cook for 5 minutes, or until just softened. For the mac cheese, heat a large sauté pan or flameproof casserole over a medium heat.

How to make mac n cheese less watery