Step 1Pound each breast between sheets of parchment or wax paper until 1/2 inch thick, then dip in flour to coat well.
Step 2Heat oil in large skillet. Fry chicken until browned, about 5 minutes per side. Remove from skillet and keep warm. Add onions, parsley and mushrooms to skillet and cook until softened, about 10 minutes. Return chicken to skillet and sprinkle with garlic salt to taste. Add Marsala and simmer until sauce reduces and thickens, 5 to 10 minutes.