Pumpkin Soup

My local Greengrocer has a very impressive array of pumpkins proudly sitting in his window so this weekend i plan to make this:
Cream of Pumpkin Soup

Ingredients:

2 lbs/900g of pumpkin (peeled, seeds removed and chopped)
I large onion (roughly chopped)
1 large potato (peeled and chopped)
1 large carrot (peeled and chopped)
1 stick of celery (chopped and thick strings discarded)
1.5 pts/700 ml of vegetable stock or add two tsp of stock powder to the same amount of water.
1 vegetable stock cube
1oz/25g of butter
half pt of cream
2 tbl spoons of chopped chives to garnish
Salt and pepper to taste
Preparation time 25 mins
Cooking time approx. 30 mins

Method:

Melt the butter in a large heavy bottomed saucepan and add all the vegetables.
Cook gently for 5 mins, stirring occasionally. Don’t allow the vegetables to brown.
Pour in the stock and add the stock cube and stir.
Simmer gently until the vegetables are just cooked (about 20 minutes) and then purée with an electric blender.
Return the puréed vegetables to the saucepan and season to taste. Add another 1/2 tsp of stock if it needs lifting.
Add the cream and re heat very gently and thin with more stock if necessary.
Sprinkle with the chopped chives and serve with massive chunks of bread.