Peel the butternut squash and cut into cubes. Slice the peppers. Peel the garlic cloves and crush using the flat of a knife.
Add the squash, peppers and garlic to a large baking tray and toss with 1 tablespoon of olive oil plus a generous pinch of salt and pepper.
Bake for 35-45 minutes, tossing everything after 20 minutes. The squash should be soft and beginning to caramelise.
Heat the remaining tablespoon of olive oil in a large pot over medium heat. Add the diced onion and cook for 5 minutes until soft. Stir in the harissa paste.
Tip the roasted squash, peppers and garlic into the pot then pour over the stock.
Bring to a boil and simmer for 5 minutes.
Blend the soup using a stick blender or by transferring in batches to a stand blender.
Season to taste - feel free to stir in some more harissa paste or add a drizzle of cream!
Notes
*You can also use regular Harissa. If you can't get hold of harissa, you can substitute it for another spicy red chilli paste such as sriracha, gochujang or Chinese garlic-chilli sauce.