Heat the oil in a large saucepan over a medium heat, add the onion and fry for 2–3 minutes until soft. Add the garlic, butternut squash and carrots and fry for a further 2 minutes, then stir in the curry powder, tomato purée, vegetable stock and mango chutney and mix well. Bring to the boil, then reduce the heat, cover and simmer for about 10 minutes.