Wash and trim the leeks
and slice the white parts very finely. Melt
the butter in a saucepan
large enough to contain all the ingredients and stew
the leeks until soft. Add the potatoes
and stir to mix. Pour in the stock and season with salt and pepper. Bring to a boil, then simmer
Allow to cool a little, then whizz the whole lot in a blender
until smooth. Leave to get cold, and stir in the cream. Check the seasoning, adding some pepper. Chill thoroughly for 6 hours to overnight. Serve in nice little bowls with snipped chives sprinkled on top.