In a saucepan, cook the pancetta in the butter. Add the other onion, garlic and sauté for 2 minutes. Add the tomatoes, broth, beans, cream and the second sprig of thyme. Season with salt and pepper. Bring to a boil and simmer for 1 hour. Cut the sausages into 1-cm (1/2-inch) thick slices and add to the saucepan with the parsley. Continue cooking for 15 minutes. Adjust the seasoning. Freeze when cooled.