Heat the butter in a large saucepan. Add the spring onions, leek, celery and potato. Stir and put on the lid. Sweat for 10 minutes, stirring a couple of times.
STEP 2
Pour in the stock and cook for 10 – 15 minutes until the potato is soft.
STEP 3
Add the spinach and cook for a couple of minutes until wilted. Use a hand blender to blitz to a smooth soup.