Splash a little olive oil into a non-stick frying pan and add the pancetta and onion. Cook over medium–high heat until onion is translucent.
Add the garlic and cook for a further minute.
Add the tomatoes and water, a pinch of salt, a good grind of black pepper and the chilli flakes. Stir and bring to the boil.
Reduce heat, add cannellini beans, cover and simmer for 30 minutes.
Add the fresh basil leaves. Taste and add salt and pepper if it needs it.
Meanwhile bring a large pot of water to the boil. Add a good pinch of salt and the pasta. Stir and bring back to the boil. Cook until pasta is al dente.
Drain and add straight into the fagioli sauce. Stir to combine.
Spoon into bowls and serve with Parmesan if desired.