1. Butterfly each chicken breast by cutting it almost in half, then open it like a book to make a large, thin piece. Place the chicken in a single layer in a glass casserole dish and sprinkle it with the lemon juice, one teaspoon of oil and seasonings. Cover and marinate in the refrigerator for several hours or overnight.
2. Heat one tablespoon of oil in a large, nonstick skillet. Add the mushrooms and garlic. Sprinkle lightly with salt and pepper and sauté on medium–high heat for about five minutes, or until golden. Remove the pan from the heat and transfer the mushrooms to a bowl.
3. Return the pan to the heat and pour in the marinade from the chicken. Add the chicken breasts to the hot marinade and brown on medium-high heat for three to four minutes per side, until cooked through. Remove the chicken from the pan. Stir in the wine and scrape up any browned bits from the bottom of the pan. Return the chicken and mushrooms to the pan and cook for two to three minutes longer to heat through. Sprinkle with parsley.