Put the beans into a heatproof earthenware pot or large pan and cover with cold water. Bring to the boil and cook gently, allowing one hour if using fresh beans, 1½-2 hours if using dried. Alternatively, you may use tinned beans.
Don't salt the water or the skins will remain tough. When soft, drain and puree half of the beans in a blender or food processor, then mix together with the whole beans.
Heat the olive oil in a saucepan, add the onion and bacon and fry until softened. Add the basil, rosemary, stock, chilli if using, tomato puree, beans and salt and pepper to taste.
Bring to the boil, then add the pasta and cook for 7-8 minutes or until the pasta is al dente.
Leave to stand for 30 minutes before serving to allow the flavours to mingle. Reheat if you like, but in Italy soups are more often served warm rather than hot, even cold in summer. Top each portion with a drizzle of extra virgin olive oil.Original recipe by Antonio Carluccio.Recipe reprinted with permission of Life is a Zoo Biscuit. To see more recipes, click here.