Potato and onion soup

1) Melt the butter in a saucepan and cook the onions until soft.
2) Add the stock to the saucepan and bring to the boil.
3) Add the potatoes and cook for 10 minutes or until soft.
4) Add the milk, then blitz with a hand blender until smooth. Check the seasoning.
5) Serve with parsley sprinkled on top.