Begin by slicing your chicken breasts in half. Next, Pound the chicken breasts with a mallet until they are thin and the meat is evenly distributed.
Then either in a large bowl or a plastic ziplock bag add the flour, salt, pepper and the chicken. Shake the chicken in the salt, pepper, and flour mixture.
Next add the butter to skillet. Once butter begins to melt, adjust to a medium setting and cook chicken breasts for about three minutes per side.
Remove the chicken and set aside. Add shallots and mushrooms to skillet and sauté. Add Marsala wine and then bring to a boil, reduce temperature and add cream and lemon juice.
Scrape bottom of the pan and then add the chicken breasts back to skillet. Cook for about ten more minutes or until chicken is finished cooking.