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 bowl, whisk together the flour, salt, and black pepper until evenly combined.
03 - Dredge each pounded chicken breast in the seasoned flour mixture, coating both sides evenly. Shake off any excess flour and set aside.
04 - Heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Once the oil shimmers, add the chicken breasts in a single layer. Cook for 4 to 5 minutes per side until golden brown and cooked through. Transfer to a plate and tent loosely with foil.
05 - Add the remaining 1 tablespoon of olive oil to the same skillet. Add the sliced mushrooms and sauté for 4 to 5 minutes until deeply browned. Stir in the minced garlic and cook for 30 seconds until fragrant.
06 - Pour the Marsala wine into the skillet, 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.
07 - Pour in the chicken broth and bring to a gentle simmer. Continue simmering for 3 to 4 minutes, allowing the flavors to meld and the liquid to reduce slightly.
08 - Return the seared chicken breasts to the skillet, spooning the mushroom sauce over the top. Simmer together for 3 to 5 minutes until the chicken is heated through and the sauce has thickened to your liking. Garnish with fresh chopped parsley and serve immediately.