This recipe is as delicious as it is easy.  With a food processor, it whips up in a snap.  I pulled this from The New York Times Cook Book, edited by Craig Claiborne.

1 pound fresh mushrooms
1 quart chicken broth (I use vegetable bouillon)
1 medium onion, chopped
7 tablespoons butter
6 tablespoons flour
3 cups milk (I use 2%)
1 cup heavy cream (I use light cream)
1 teaspoon or more salt
White pepper (I use fresh ground black pepper)
Tabasco sauce
2 tablespoons sherry (I have yet to do this but it sounds delicious!)

Instructions (modified slightly from the original)
Wash the mushrooms and trim stems if needed.  Slice six caps and reserve.  Chop the mushrooms in a food processor and transfer to a large soup pot.  Chop the onion in the food processor and add to mushrooms.  Add broth and simmer for 30 minutes.

Saute the reserved sliced caps in 1 tablespoon of butter and reserve for garnish.

Melt remaining butter in a saucepan, add the flour, and stir with a wire whisk until blended, making a roux.  Meanwhile, bring the milk to a boil and add all at once to the roux, stirring vigorously with the whisk until the sauce is thickened and smooth.  Add the cream.

Add cream sauce to the mushroom broth and season to taste with salt, pepper, and Tabasco.  Reheat and add the sherry before serving.  Garnish with sauteed sliced mushrooms.  Delicious served inside a lightly toasted bread bowl as a main course or with toasted chiabatta or baguette as a starter or lunch course.