In a large pot, melt the butter. Add the leeks and cook over a low heat until soft, about 5 minutes.
Add the potatoes and pour over the stock. Cover and cook for 20 – 30 minutes or until the potatoes are soft enough to puree.
Strain the stock into a separate bowl.
Add a ladle of the stock at a time and puree the vegetables and stock until it forms a light & creamy consistency.
Serve hot with the cheese and chives sprinkled on top.
