Melt butter in a Dutch oven or heavy saucepan over medium heat. Add onion, garlic, celery, thyme, salt and pepper and cook until soft and fragrant, about 3 minutes. Add the mushrooms and cook until they are golden brown, approximately 5 minutes.
Add the flour and stir until veggies are coated. Add white wine and stir until lumps are gone. Turn heat to medium-high and add the broth. Bring to a boil and reduce to a simmer over medium-low. Simmer for 20 minutes, stirring occasionally. Remove from the heat and let cool for 20 minutes.
Pour the cooled soup mixture into a blender and puree until smooth. Pour back into the Dutch oven and cook over medium heat for 5 minutes or until heated through. Add heavy cream and cook until warm. Serve warm with thyme on top!
Notes
Be absolutely sure that you allow the soup to cool before blending it!
Another option for making the soup creamier is to use an immersion blender or even a potato masher, depending on how smooth you want it to be.
The white wine in the recipe is optional, but adds incredible flavor!
For a beautiful presentation (since, uh, the soup itself is not super beautiful), lay a few fresh thyme leaves over the top before serving.
Chicken and vegetable broth can be used interchangeably in this recipe.
Any type of mushrooms work great in this soup, even the standard white variety that is easily found in the produce aisle.