Heat the olive oil in a large heavy pot over medium-low heat. Add the onion, celery, and carrots with a pinch of salt and cook for 10 minutes, stirring occasionally, until the onion is pale and completely soft.

Add the garlic and cook for 2 minutes until fragrant but not colored. Stir in the tomato paste and cook for 1 minute until it darkens slightly.

Add the crushed tinned tomatoes to the pot and stir well, scraping up any bits from the base. Cook for 3 minutes until the tomatoes reduce slightly.

Pour in the vegetable stock. Add the Parmesan rind, dried thyme, and bay leaf. Bring to a gentle simmer over medium heat.

Add the diced potato and cook for 10 minutes until just starting to soften.

While the potato cooks, take one-third of the drained cannellini beans and crush them roughly with a fork or the back of a spoon. Add all the beans (whole and crushed) to the pot and stir to combine.

Simmer for 10 minutes until the broth thickens and the potato is cooked through. Add the cavolo nero strips and cook for a further 8 minutes until tender but still vivid green.

While the soup finishes, cook the ditalini in a separate pot of well-salted boiling water until al dente according to packet instructions. Drain and set aside.

Remove and discard the Parmesan rind and bay leaf. Taste the soup and adjust salt and pepper.

Rest the soup off the heat for 5 minutes. Spoon pasta into each bowl, ladle the hot soup over the top, drizzle with extra-virgin olive oil, and finish with grated Parmesan.