Heat the oil in a saucepan. Add the onion and fry for 3 minutes until softened. Add the celery and garlic and fry for 2 minutes.
Add the butter beans, sun-dried tomato paste, stock, rosemary or thyme and a little salt and pepper. Bring to the boil, then reduce the heat, cover and simmer gently for 15 minutes. Serve sprinkled with the Parmesan shavings. This soup makes a light main course served with bread and plenty of Parmesan.