- Heat the butter in a large saucepan and add the onion, potato and celery. Fry until the onion begins to soften.
- Add the apple, water and stock. Season well with salt and pepper. Bring to the boil and then turn down to simmer for 15 minutes.
- Blitz with a hand-held blender. Add the milk and bring back to the boil.
- Serve with the chives sprinkled over and some crusty bread, or cheese on toast.