01 - Place each chicken breast between two sheets of parchment paper and gently pound with a meat mallet to an even ½-inch thickness throughout.
02 - In a shallow dish, whisk together the flour, salt, and black pepper. Lightly dredge each pounded chicken breast in the seasoned flour, shaking off any excess coating.
03 - Heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Add the dredged chicken breasts and cook for 4 to 5 minutes per side until golden brown and cooked through. Transfer to a plate and tent loosely with foil.
04 - Add the remaining 1 tablespoon of olive oil to the same skillet. Sauté the sliced mushrooms for 4 to 5 minutes until deeply browned. Stir in the minced garlic and cook for 30 seconds until fragrant.
05 - Pour in the dry Marsala wine, using a wooden spoon to scrape up any browned bits from the bottom of the pan. Let the wine reduce by half, about 2 to 3 minutes.
06 - Pour in the chicken broth and bring to a gentle simmer. Cook for 3 to 4 minutes, allowing the flavors to meld and the liquid to reduce slightly.
07 - Nestle the seared chicken breasts back into the skillet, spooning the mushroom sauce over the top. Simmer for 3 to 5 minutes until the chicken is heated through and the sauce has thickened to a glossy consistency.
08 - Sprinkle generously with chopped fresh parsley and serve immediately while hot.