In a large pot over medium heat, add the chopped onion, carrots, and celery. Sauté for about 5 minutes until softened.

Add the sliced mushrooms and minced garlic. Cook for an additional 5 minutes until the mushrooms are tender.

Pour in the chicken broth and bring the mixture to a simmer.

Stir in the shredded rotisserie chicken, thyme, salt, and pepper.

In a small bowl, whisk together the heavy cream and flour until smooth. Gradually add this mixture to the soup, stirring constantly to avoid lumps.

Let the soup simmer for about 15 minutes, stirring occasionally, until it thickens slightly.

Taste and adjust seasoning with additional salt and pepper if necessary.

Ladle the soup into bowls and garnish with chopped fresh parsley before serving.