Wipe the mushrooms with paper towel and trim the stems. Slice 6-8 of the mushrooms and set them aside. Chop the remaining mushrooms.
In a medium pot, heat 6 tablespoons of the butter. Add the onion, season with a little salt and saute until softened. Add the chopped mushrooms and saute until tender. Stir in the flour and cook for 1 minute. Add the white wine and stir for another minute. Pour in the stock, thyme and bay leaf. Season with salt and pepper and bring to a boil. Reduce the heat and simmer for 10 minutes.
While the soup simmers, melt remaining butter in a saute pan. Add the sliced mushrooms and cook until golden and tender. Set aside.
Discard the bay leaf. Use a stick blender to puree the soup, then stir in the half-and-half, milk and reserved mushrooms. Season with more salt and pepper, if needed.
Recipe by white plate blank slate at https://whiteplateblankslate.com/creamy-mushroom-soup/