Start by melting the butter in a large saucepan over medium heat.
Add in the onion, carrots and celery and sauté covered until soft, about 12 minutes.
Add in the flour and cook for another 2 minutes, stirring occasionally.
Add in the chicken broth or stock and bring mixture to a boil, whisking continuously.
Tie the thyme, bay leaf and parsley sprigs together with kitchen twine, and add into the soup.
Lower the heat until mixture is at a simmer. Continue simmering for about 15 minutes, allowing mixture to thicken.
Add in the chicken and bring soup back to a boil, then remove from heat.
Pour in the heavy cream, sherry and salt, whisking together until combined. Remove the herb bundle, and season with pepper to taste. Ladle into bowls, garnish with chopped parsley, and enjoy!
Notes
Store your soup in an airtight container, where it will keep in the fridge for about a week.