01 - Place each chicken breast between sheets of parchment paper and gently pound with a meat mallet to an even 1/2-inch thickness throughout.
02 - In a shallow dish, combine the all-purpose flour, kosher salt, and black pepper until evenly mixed.
03 - Lightly coat each pounded chicken breast in the seasoned flour mixture, shaking off any excess to ensure a thin, even coating.
04 - 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 loosely tent with foil.
05 - Add the remaining 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.
06 - Pour the dry Marsala wine into the skillet, scraping up any fond from the bottom of the pan. Cook for 2 to 3 minutes until the liquid reduces by half.
07 - Pour in the chicken broth and bring to a simmer. Cook for 3 to 4 minutes, allowing the flavors to meld and the sauce to begin reducing.
08 - Return the seared chicken to 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 slightly. Garnish with fresh chopped parsley and serve immediately.