Preheat your oven to 275°F (135°C).

Slice the chicken breasts in half by slicing them horizontally through the thickest part. Season the chicken breast halves on both sides with salt and pepper.

Heat the 1 tablespoon of olive oil in a large non-stick skillet. Sear the chicken breast halves on both sides for 5-6 minutes or until cooked through. You may have to work in batches of 2 or 3 chicken breast halves at a time.

Transfer the cooked chicken breast halves on a sheet tray and set aside.

In a small bowl, combine the parmesan cheese, mozzarella cheese, bread crumbs, melted butter, sun-dried tomatoes, and italian parsley. Mix well to create the cheese filling.

Divide the cheese filling evenly among 3 of the chicken breast halves, placing it in the center of each breast and spreading evenly. Place the other chicken breast halves on top of the cheese filling.

Place the baking sheet with the stuffed chicken in the preheated 275°F (135°C) while you make the sauce. This will keep the chicken warm and melt the cheese filling.

In the same skillet you seared the chicken in, melt the 3 tablespoons of butter over medium heat. Add the sliced mushrooms and cook for 5-6 minutes, or until tender and browned.

Stir in the minced garlic and salt, cooking for an additional 1 minute.

Stir in the 2 tablespoons of flour, mix until well combined, cooking for an additional 2 minutes.

Pour in the marsala wine, stir to combine with flour and bring the mixture to a boil. Reduce the heat and simmer for 5 minutes or until the sauce has thickened and reduced slightly.

Stir in the heavy cream and cook for an additional 2-3 minutes, or until the sauce has thickened.

To serve, place the cooked pasta on a plate, top with a stuffed chicken breast, and spoon the marsala sauce over top. Garnish with fresh italian parsley, enjoy!