- Melt the butter over medium-high heat in a large soup pot. Add the onion and cook for about 5 minutes, until it begins to soften and brown. Add the celery and cook about 3 more minutes until it softens slightly.
- Stir in the mushrooms and continue to cook until they darken and shrink, about 3 more minutes. Add the potatoes, salt, and pepper. Stir well. Stir in the flour to coat all the ingredients.
- Pour in the stock and bring the soup to a boil. Reduce the heat and simmer, stirring occasionally, for 7 to 10 minutes, until the potatoes are tender. Reduce the heat to low, stir in the cream. Add additional salt and pepper if desired.
- Remove from the heat and serve garnished with chopped celery leaves or fresh parsley.
Click here to see the recipe on the Mushroom Council's website.