Begin by seasoning the chicken breasts with salt and pepper on both sides. Dredge each breast in flour, shaking off any excess.
In a large skillet, heat the olive oil over medium-high heat. Once hot, add the chicken breasts and cook for about 4-5 minutes on each side, or until golden brown and cooked through. Remove the chicken from the skillet and set aside.
In the same skillet, add the sliced mushrooms and sauté for about 5 minutes until they are browned and tender. Add the minced garlic and cook for an additional minute until fragrant.
Pour in the Marsala wine, scraping the bottom of the skillet to deglaze. Allow the wine to simmer for about 2-3 minutes until it reduces slightly.
Add the chicken broth and bring the mixture to a simmer. Return the chicken to the skillet and cook for another 5 minutes, allowing the flavors to meld.
Stir in the butter until melted and the sauce is smooth. Adjust seasoning with salt and pepper if needed.
Serve the chicken hot, spooning the mushroom sauce over the top and garnishing with chopped parsley.
Notes
For a creamier sauce, add 1/4 cup of heavy cream to the skillet after adding the chicken broth.
Serve over pasta or mashed potatoes for a heartier meal.