Cream of Mushroom Soup

1 pound mushrooms
1 lemon juice
3 ounce butter
1 shallot or 1 tablespoon onion, chopped
1 small clove garlic
Salt & pepper
2 ounce flour
2 pint beef stock
4 oz.
Double cream

Make a duxelles as follows. Chop garlic finely and add, with the onions or shallots, to 1/3 of the butter in a pan. Sweat, then cook gently till golden. Meanwhile prepare mushrooms, chop and sprinkle with lemon juice. When onions/shallots are golden, add mushrooms and cook. If they exude a great deal of liquid, strain and boil down separately to avoid overcooking the mushrooms. Season with salt, pepper and nutmeg. Make a roux from remaining 2 ounce of butter and the flour. Add stock and make a sauce as usual. Simmer 20 minutes. Add mushroom duxelles and cook a further 10 minutes. Just before serving, correct seasoning and add cream.