1. Melt the butter with the olive oil in a large heavy pot or Dutch oven over medium high heat.

2. Add the sliced mushrooms in an even layer and cook without stirring for 2 to 3 minutes so they begin to brown, then stir and continue cooking until golden and most of their liquid has evaporated.

3. Stir in the diced onion and cook for 3 to 4 minutes, until softened and translucent.

4. Add the minced garlic and cook for 30 seconds, just until fragrant.

5. Sprinkle the flour evenly over the mushrooms and onions, stirring constantly for 1 to 2 minutes to coat the vegetables and cook off the raw flour taste.

6. Slowly pour in the chicken broth while stirring or whisking to prevent lumps, followed by the white wine if using.

7. Add the thyme and bay leaf, bring the soup to a gentle simmer, and cook for 5 to 7 minutes, stirring occasionally, until slightly thickened.

8. Stir in the shredded rotisserie chicken and reduce the heat to low.

9. Pour in the heavy cream or half and half, stirring to combine, and let the soup simmer gently for another 5 to 8 minutes until the chicken is warmed through and the broth is creamy.

10. Season with salt and black pepper to taste, then add the lemon juice if using and adjust seasoning as needed.

11. Remove the bay leaf, stir in the chopped fresh parsley, and ladle the soup into bowls.

12. Garnish with additional parsley and freshly ground black pepper, then serve hot with crusty bread or garlic toast if desired.