1. Melt the butter in a stockpot over medium-high heat.
2. Add the sliced mushrooms, 1 teaspoon of salt and sauté for 5 minutes until they are lightly browned.
3. Add the onion, carrot, and celery, 2 teaspoons of salt and 1 teaspoon of pepper cook until they begin to soften.
4. Sprinkle the flour and cook for 30 seconds, stirring until the four is cooked (it will have a nutty fragrance).
5. Add the chicken stock scraping the bottom in case any flour sticks.
6. Then add the rice, bay leaf, and thyme.
7. Bring the soup to a boil, lower the heat and simmer for 30-45 minutes or until the rice is cooked through.
8. When the rice is done discard the bay leaf. Stir in the heavy cream and shredded chicken. Taste for seasonings.
9. Serve in warm soup bowls and garnish with lots of fresh parsley.