In a large heavy saucepan, cook mushrooms in the broth with onion and thyme until tender, about 10 to 15 minutes.
In blender or food processor, puree the mixture , leaving some chunks of vegetable in it. Set aside.
In the saucepan, melt the butter, whisk in the flour until smooth. Add the salt, pepper, half and half and vegetable puree. Stirring constantly, bring soup to a boil and cook until thickened. Adjust seasonings to taste, and add sherry.
I remember while I was student sharing a small apartment with 3 other girls, there was not much to cook with as we were living pay check to paycheck. Our go to meal was cream of mushroom soup, it was economical and most of the time half of the can remain for the next meal.
We didn't really cook, we just opened the can and heated it up and the smell wafting in the air smelled like home. It was so creamy and comforting and the aroma filled the empty space of the flat, giving the illusion that we were not alone and there was love in the house.
Now when I cook this soup, I am always reminded of that period of my life and it brings a smile to my face knowing that I am in a better place and I can afford to feed my family healthy home made meals.