Heat a large saucepan over a medium heat and sauté the leek, carrot, celery and shallot with a pinch of salt until soft and glossy.
Add plenty of black pepper, minced garlic and the rosemary sprig, and cook for 30 seconds until fragrant.
Crumble in the stock cube and pour over about 1 litre of boiling water.
Add the Parmesan rind and bring to a gentle simmer.
Lower in the chicken breasts and poach gently for 12–15 minutes until just cooked through.
Remove the chicken and set aside to cool slightly, then shred.
While the soup is simmering, combine the sliced chillies with enough white wine vinegar to cover and a good pinch of sugar. Set aside to lightly pickle.
Add the cannellini beans to the soup, followed by the cornflour slurry, stirring well.
Simmer for a few minutes until the broth thickens, adding more cornflour if needed.
Add the cavolo nero or kale and cook until tender.
Return the shredded chicken to the pan.
Remove the rosemary sprig and Parmesan rind, then stir through the grated Parmesan.
Taste and season with more black pepper and salt if needed.
Serve hot, topped with the pickled chillies, extra Parmesan and plenty more black pepper.
