Peel and finely chop the onion. Warm a large pan on a medium heat for a few mins then pour in 1 tbsp olive oil and add the onion. Fry on a low heat for 5-6 mins till glossy. Stir regularly.

While the onion fries, peel and grate or crush the garlic. Peel and chop the carrots into 2cm-thick slices. Fill and boil the kettle.

Add the garlic to the pan and cook for 1 min, stirring, then add the carrots and the cooked chestnuts with a good pinch of salt and pepper. Stir together, then pour in 700ml hot water from the kettle. Pop on a lid and simmer for 20 mins.

While the soup simmers, trim the Brussels sprouts and discard any ragged leaves. Finely slice the sprouts. Halve the chilli and flick out the seeds and white bits. Finely chop half the chilli. Peel and finely grate the ginger.

Warm a frying pan on the heat for a few mins then add 1 tbsp olive oil and the sprouts, chilli and ginger with a pinch of salt. Fry for 3-4 mins, stirring, till the sprouts have softened and are beginning to brown at the edges. Tip the sizzled sprouts into a bowl.

After 20 mins, the carrots should be soft. Using a hand-held blender in the pan, blend the soup till really smooth, or ladle it into a blender and blitz. Add more liquid if the soup seems too thick. Taste and add more salt or pepper if you think it needs it. Ladle the soup into 2 warm bowls and top with the sizzled sprouts to serve.