Step 1: Sauté the Vegetables

1. Heat olive oil in a large pot or Dutch oven over medium heat.
2. Add the diced onion, celery, and carrots. Cook for 5-7 minutes until the vegetables are softened.
3. Stir in the garlic and cook for an additional minute until fragrant.

Step 2: Cook the Mushrooms

1. Add the sliced mushrooms to the pot and cook for 5-7 minutes until they release their liquid and start to brown.

Step 3: Add the Wild Rice and Broth

1. Stir in the wild rice, chicken broth, bay leaf, thyme, and rosemary. Season with salt and pepper to taste.
2. Bring the mixture to a boil, then reduce the heat to low. Cover and simmer for 35-40 minutes, or until the rice is tender.

Step 4: Prepare the Cream Base

1. In a small saucepan, melt the butter over medium heat.
2. Whisk in the flour and cook for 1-2 minutes to remove the raw flour taste.
3. Gradually whisk in the milk, stirring constantly to avoid lumps. Cook until the mixture thickens, about 3-5 minutes.
4. Stir in the heavy cream and remove from heat.

Step 5: Combine and Finish

1. Once the rice is tender, add the cooked chicken to the soup. Stir to combine.
2. Slowly pour the cream base into the soup, stirring until fully incorporated. Simmer for an additional 5-10 minutes to thicken and blend the flavors.

Step 6: Serve

1. Remove the bay leaf and adjust seasoning with more salt and pepper if needed.
2. Ladle the soup into bowls and garnish with fresh parsley, cracked black pepper, or Parmesan cheese, if desired.