Asparagus Soup

Remove the white part of the asparagus stems and peel them leaving the heads intact. Cook in boiling salted water just until soft. Remove and dip them in iced water to stop them cooking. Cut the heads off, reserve, and chop the stems coarsely. Melt the butter in a pan and add the flour. Cook the flour until the mixture looks creamy, then add the chicken stock, a little at a time, mixing constantly. Bring to the boil and let it cook for 20 minutes. Remove from the heat and blend with the chopped asparagus stems. Season with salt and pepper. Pass the soup through a sieve and take it to the heat again, without letting it boil. Mix in the cream and the asparagus tips just to reheat them. Serve.