First, pre-heat the oven to gas mark 4/350F/180C and line a roasting tray with foil or parchment.
Cut the butternut squash into bite-size chunks, then line up on the tray and spray with a little cooking spray. Roast for 30-40 minutes until tender, stirring halfway.
Meanwhile, rinse the lentils before adding to a pot along with the stock cube and covering with cold water. Bring to the boil, then allow to simmer for 12 minutes.
Heat some cooking spray on a non-stick pan and add the onions. Fry until soft, then add the curry paste, tomatoes and coconut milk. Stir every so often as the sauce thickens (about 10 minutes). Meanwhile, heat up the naan bread in the oven.
Finally, add the squash, lentils and spinach to the curry and season to taste. Cook for another couple of minutes, then serve with the naan bread.
Notes: I adapted this (with little change) from a BBC recipe to cook for my mum on our vegan nights because we both LOVE curry and this was a hit!