Prep your onion, carrots, and celery. I just roughly chopped the carrots and celery.
Add the oil and butter to a large soup pot over medium-high heat. Add the onion, carrots, and celery. Sauté for 7 minutes, stirring occasionally.
Stir in the garlic, Italian seasoning, and flour. Cook for 1-2 minutes.
Whisk in the chicken broth until the flour is dissolved.
Stir in the rice.
Increase the heat to high and bring the soup to a boil. Once it's just boiling, cover the pot with the lid slightly ajar. Reduce the heat so it's gently boiling for 15 minutes.
If you haven't already prepped the turkey and mushrooms, you can do it now.
Add the turkey and mushrooms to the soup. Increase the heat again so it just comes to a boil, then reduce the heat so it's simmering again and continue cooking the soup for another 15-20 minutes (cover with lid slightly ajar) or until the rice is tender (wild rice does have a bit of "chew" to it, though).
Stir in the cream (if using). Season soup with salt & pepper as needed.