Pre-heat the oven to 390 ºF (200 ºC) and line a large baking tray with baking/greaseproof paper.
In a large bowl, toss the chunks of butternut squash with 1 tbsp of oil and a pinch of salt and pepper.
Transfer the chunks onto the lined baking tray and spread them out evenly so that they form a single layer.
Roast the butternut squash chunks at 390 ºF (200 ºC) for 45 minutes - 1 hour, until soft and caramelised.
Add the onions with 1 tbsp olive oil and a generous pinch of salt into a large skillet.
Cook the onions for 10 - 15 minutes on medium-low heat, stirring frequently, until softened and caramelised.
Combine the roasted butternut squash and caramelised onions in a deep pot.
Add a generous pinch of salt, pepper and nutmeg.
Add about 2 cups of boiling hot water and blend (with a hand/stick blender, or transfer into a large blender or food processor) until smooth and creamy.
Add more hot water until you reach the desired consistency. Adjust seasoning as needed.
Serve the soup topped with some yogurt (use a non-dairy yogurt alternative to keep this recipe vegan) and a few crispy sage leaves fried in olive oil.
The roasted butternut squash soup keeps well in the fridge in a closed container for about 1 week. Reheat it on the stovetop or in the microwave as needed.
Recipe by The Loopy Whisk (www.theloopywhisk.com).