In a 4-quart Dutch oven, melt butter over medium heat. Add onion, garlic, mushrooms, salt, and pepper. Cook, stirring frequently, until mushrooms are soft and have released their liquid, 10 to 12 minutes.
Stir in flour until mushrooms are well coated; cook, stirring frequently, until golden brown, 3 to 5 minutes. Gradually stir in mushroom stock; cook for 2 minutes, scraping browned bits from bottom of pot with a wooden spoon. Stir in chicken broth, Worcestershire, and thyme; bring to a boil. Reduce heat, and simmer, stirring occasionally, until slightly thickened, 20 to 30 minutes.
Remove from heat; gradually stir in cream until combined. Serve immediately.
Notes
*We used College Inn Mushroom Stock.
KITCHEN TIP: This soup freezes well; reheat it over medium-low heat, stirring frequently, until soup is hot but not boiling.
Recipe by Southern Cast Iron at https://southerncastiron.com/cream-mushroom-soup/