Saute mushrooms in butter until brown. Add wine when mushrooms start making their own juice; cook over medium heat until all liquid evaporates and clear oil from butter is in pan, about 10 minutes.
Add flour and cook on high about 5 minutes; stir and blend, cook till nut-brown. (Like a medium brown roux, except for mushrooms and is wine-colored.) Can add more butter as necessary to make a smooth "sauce" texture. Stir constantly.
Stir in half-and-half (can substitute milk) until you have the thickness or amount of soup you want; stir to creamy consistency. Salt and pepper to taste. Makes about 1 1/2 to 2 cups soup.