Preheat oven to 200 ̊C/400 ̊F
Place the squash into a large bowl. Add the onion and carrots. Add 1 tbsp oil / butterand salt and pepper and toss everything together until the vegetables are evenlycoated. Transfer to a large toasting tin and spread out to form an even laye.
Roast for 35 minutes, or until tender.
Heat the remaining oil / butter in a large saucepan over a medium heat. Add the gingerand chilli (if using) and fry for one minute, stirring.
Add the stock and bring to a simmer, then add in the roasted vegetables. Add thecooked lentils, salt and pepper and stir well.
Remove the saucepan from the heat. Blend in batches, until smooth.
Serve with crème fraîche, if using.
Store any leftovers in an airtight container and refrigerate for up to 4 days or freeze on the same day.