Season the chicken: Sprinkle chicken with salt, pepper, garlic powder, onion powder, and thyme.
No need to marinate—just coat it well.
Layer the aromatics: In your slow cooker, Instant Pot, or a baking dish, add mushrooms, onion, and garlic. Place the seasoned chicken on top.
Mix the sauce base: Whisk Marsala wine, chicken broth, and Dijon mustard. Pour over the chicken and vegetables.
Cook it your way: Slow cooker: Low for 4–5 hours or High for 2–3 hours, until chicken is tender.
Instant Pot: Manual/Pressure Cook for 8 minutes (thighs) or 10 minutes (breasts), then quick release.
Oven: Cover and bake at 350°F (175°C) for 35–45 minutes, until chicken reaches 165°F.
Thicken the sauce (optional but nice): Transfer the cooking liquid to a saucepan.
Whisk cornstarch with 2 tablespoons cold water, then stir into the sauce. Simmer 2–3 minutes until slightly thickened.
Make it creamy: Stir in heavy cream and butter. Simmer on low for 2–3 minutes.
Taste and adjust salt and pepper.
Combine and serve: Pour the creamy Marsala sauce over the chicken. Garnish with parsley and serve with your favorite side.