Blanch the almonds and grind in a Mouli grater or a blender. Place in a saucepan along with the washed and cut up celery and the chopped onion. Add the hot chicken stock and bring up to the boil. Lower the heat, cover and simmer gently for 1 hour. Draw off the heat and strain the liquid, pressing well to extract all the flavour.
Melt the butter and stir in the flour. Gradually add the a