Heat a large pot over medium and add the butter or oil. Melt until it foams.

Add the chopped onion, carrots, and celery. Cook, stirring occasionally, for 5 to 7 minutes until the vegetables soften and begin to color.

Add the sliced mushrooms. Cook for 6 to 8 minutes, stirring now and then, until they give up their moisture and start to brown.

Stir in the minced garlic and cook for about 30 seconds until fragrant.

If using flour, sprinkle it over the vegetables and stir to coat. Cook for 1 minute to remove the raw flour taste.

Slowly pour in the chicken stock while stirring to prevent lumps. Add the bay leaf and thyme. Bring the pot to a gentle simmer.

Let the soup simmer for 10 minutes so the flavors meld and the broth reduces slightly.

Add the shredded rotisserie chicken and simmer for 3 to 5 minutes just to warm the meat through.

Stir in the cream or half-and-half. Taste and adjust salt and pepper.

Remove the bay leaf. Finish with chopped parsley or chives and serve with crusty bread or buttered toast.