• If using ready-made cannellini beans stored in glass or tin, rinse under running water and set aside. For dried beans, read the instructions at the bottom of the recipe.
• Keeping the vegetables separate, finely chop the onion, carrot, and celery.
• In a casserole over low heat, melt the butter in the olive oil. Add the onion and cook for 3 minutes, stirring, then add the carrot, celery, and half the parsley.
• Cook for 2 minutes, then add the cannellini beans. Turn up the heat and cook for 1 minute. Pour in the broth or water, add salt to taste, and add 100 g of potato to the pan.
• Then, cook for 10 minutes, bringing to a boil, then add the pancetta or smoked ham, lower the heat, and continue cooking over low heat for 30 minutes or until the cannellini beans are as soft as you like. I like them very soft.
• When cooked, remove 1/3 of the cannellini beans and the potato from the pan. Blend to a cream in a food processor or with a hand blender.
• Pour the cream into the pot and stir.
• Place the soup into bowls, sprinkle with parsley, add a drizzle of olive oil, and add the bread, which you can place at the bottom of the bowl and pour the soup over, or arrange on the side but inside the soup.
• Serve the soup hot with Parmigiano aside (I don't do this, but you can do as you like).

Tips

• If you prefer, use borlotti beans.
• If using dried beans, drain the beans from the soaking water, rinse under running water, and set aside. To reduce the soup's cooking time, I usually cook the beans in advance in unsalted boiling water with a few bay leaves for 30 minutes. The bay leaves are not necessary.