Prepare the Chicken: Slice each chicken breast in half horizontally to make thin cutlets. Lightly pound with a meat mallet to even thickness.
Coat the Chicken: In a shallow dish, mix gluten free flour, salt, pepper, and garlic powder. Dredge chicken pieces in the mixture, shaking off any excess.
Sear the Chicken: Heat olive oil or butter in a large skillet over medium heat. Add chicken and cook for 4–5 minutes per side, or until golden brown and cooked through. Transfer to a plate and set aside.
Cook the Mushrooms: In the same pan, add a bit more oil if needed and sauté mushrooms for about 5 minutes until they release moisture and turn golden. Add minced garlic and cook for another 30 seconds.
Deglaze with Marsala Wine: Pour in the Marsala wine and use a spatula to scrape up the browned bits from the pan. Let it simmer for 2–3 minutes to reduce slightly.
Add Broth and Simmer: Stir in chicken broth and thyme, and bring to a gentle simmer. Return the chicken to the pan and cook for another 8–10 minutes, allowing the sauce to thicken.
Optional Creamy Finish: For a richer sauce, stir in the heavy cream and let it simmer for 2–3 minutes.
Garnish and Serve: Sprinkle fresh parsley over the top and serve hot with mashed potatoes, gluten free pasta, or rice.