In a large, heavy-bottomed pot, slowly melt butter. Add garlic and cook for 2-3 minutes until the garlic becomes fragrant.
Add mushrooms, thyme, and Worcestershire sauce to the pot. Cook for 8-10 minutes and add wine. Cook for another 5 minutes until liquid is absorbed and mushrooms are cooked through.
Pour in mushroom stock. Simmer for 10 minutes.
Add evaporated milk, and half and half. Return to simmer for another 5 minutes. Remove from heat and then cool slighty.
Using a food mill (at camp) or immersion blender (at home), puree soup until smooth. Return to heat and cook for another 10 minutes.
Notes
Blending the soup adds air to the mixture. Returning it to heat helps to remove it.