In a medium Dutch oven, heat butter and oil over medium-high heat until butter is melted. Add onion and celery; cook until softened, about 4 minutes. Stir in rice and garlic; cook for 2 minutes, stirring frequently. Stir in 6 cups broth, carrot, mushrooms, thyme, parsley, 2 teaspoons salt, and pepper; bring to a boil. Partially cover; reduce heat and simmer until rice is almost tender, about 35 minutes.
Stir in chicken, cream, remaining 1 cup broth, and remaining ½ teaspoon salt; cook until rice is tender, about 10 minutes. Garnish with parsley, if desired.
Notes
*We used Lundberg Wild Blend Rice.
Recipe by Taste of the South at https://tasteofthesouthmagazine.com/chicken-rice-soup/