Heat a large Dutch oven over medium heat. Add the sausage and cook until browned, breaking it up with a spoon as it cooks.
Add the onion, carrots, and garlic to the pot. Cook for 5 minutes until the vegetables soften.
Stir in the mushrooms and cook for another 3 minutes until they start to release liquid.
Add the barley, chicken broth, and thyme. Bring the mixture to a boil, then reduce to a simmer.
Cover and cook for 35 minutes, stirring once or twice, until the barley is tender.
Remove the lid and stir in the heavy cream. Season with salt and black pepper. Simmer uncovered for 5 minutes to thicken slightly.
Ladle into bowls and top with fresh parsley before serving.