Okay, here's the scoop. The chef does make this soup from scratch but doesn't use measurements. He told me what he used to make it so now it's going to be a bit of a "hit & miss" project but it's well worth the effort.

1) Place fresh, sliced Button mushrooms and butter in a medium size sauce pan and saute.
2) Add white wine but not enough to cover the mushrooms and simmer 5-10 minutes.
3) Add enough 1/2 & 1/2 to the mixture which will become you base for the soup, i.e., lots of 1/2 & 1/2, lots of soup, etc.
4) Add a Roux (mixture of flour and butter but to keep it white, cook the flour for only a minute or two).
5) Add 1 or 2 wedges of Brie (about 6 oz.) with the skin removed.
6) Add salt to taste.
7) Roughly blend the soup until the mushrooms are tiny, little pieces using a food processor, blender or whatever method you wish.

Serve hot. This is a very hearty and filling soup. Just a cup of it with a half a sandwich or as a side dish or "starter" is perfect!