2tablespoonsunsalted butter, cut into small pieces
4tablespoonsminced fresh parsley, divided
In a shallow bowl combine the flour, ½ teaspoon salt and salt and ¼ teaspoon pepper.
Heat the oil in a very large skillet over medium high heat. Dredge the chicken breasts in the flour mixture and when the oil is hot place the cutlets in the pan and cook for about 4 minutes, until the bottom is browned, then flip and cook for another 4 or 5 minutes, until the bottom is browned and the chicken is just cooked through. Remove the chicken from the pan to a platter.
Return the skillet to medium heat and add the pancetta. Stir until the pancetta is crisp and browned, scraping up any little browned bits stuck to the bottom of the pan (you will get more of those browned bits loosened when you add the wine). Transfer the crisp pancetta to a paper towel-lined plate to drain.
Return the pan to medium high heat and add the mushrooms. Cook, stirring occasionally, until the mushrooms are browned and any liquid released by the mushrooms has evaporated, about 8 minutes. Continue to scrape the bottom of the pan to loosen any browned bits. Add the garlic and stir for one more minute until you can smell the garlic.
Add the marsala wine and broth, then return the pan to the heat and stir and scrape until all of the browned bits come loose and the wine reduces and starts to become a syrupy sauce. Add any juices that have accumulated on the plate from the chicken, then stir in the lemon juice and the butter until melted. Season with salt and pepper to taste and stir in half of the parsley, and half the crisped pancetta. Pour the sauce over the chicken on the platter, and sprinkle with the rest of the parsley and pancetta. Serve hot.