Slice the leeks, carrots and celery into 1 cm pieces, then crush or grate the garlic.

Warm 2 tbsp olive oil in a large deep saucepan over medium-low heat. Add the garlic, leeks, carrots, celery and flaky sea salt.

Cook the vegetables for 5–7 minutes, stirring occasionally. Cook until they are slightly softened.

Add the bay leaves, fresh rosemary and harissa paste to the saucepan. Stir until the vegetables are coated.

Cook the aromatics for 2–3 minutes, stirring frequently. Cook until fragrant.

Drain and rinse the canned butter beans. Open the canned cherry tomatoes.

Pour the butter beans, cherry tomatoes and vegetable stock into the saucepan. Add the maple syrup, if using.

Bring the soup to a gentle simmer. Simmer for 10–15 minutes until the vegetables are just tender.

Remove the saucepan from the heat. Blend roughly half of the soup with the hand blender to lightly thicken it.

Return the soup to medium-low heat and add the sliced cavolo nero. Cover the saucepan with a lid.

Simmer for 4–5 minutes until the cavolo nero is wilted. Season with black pepper and additional flaky sea salt to taste.

Ladle the soup into 4 serving bowls. Top with hazelnuts and drizzle with extra olive oil before serving.