Cook the Pasta: Bring a large pot of salted water to a boil. Add penne and cook until just tender. Drain and set aside. Save a little pasta water in case you need it later.
Season and Brown the Chicken: Season the chicken pieces with salt and pepper. Heat olive oil in a large skillet over medium heat. Add chicken and cook until lightly golden and cooked through. Transfer to a plate.
Build the Flavor Base: Add chopped onion to the same skillet. Cook until soft and translucent. Add mushrooms and cook until they release moisture and turn golden.
Add Garlic and Wine: Stir in minced garlic and cook briefly until fragrant. Pour in Marsala wine and let it simmer until slightly reduced. This step deepens the flavor.
Create the Creamy Sauce: Pour in chicken broth and heavy cream. Stir gently and bring to a soft simmer. Let the sauce thicken slightly.
Bring Everything Together: Return the chicken to the skillet. Add cooked pasta and toss until fully coated. Stir in Parmesan cheese until melted and smooth.
Finish and Rest: Sprinkle parsley over the top. Let the pasta rest a few minutes so the sauce settles and thickens naturally.
