Wild mushrooms help make this Marsala a masterpiece.
Shake: Combine the flour, 1/4 teaspoon salt and 1/8 teaspoon black pepper in a re-sealable plastic bag. Add the chicken to the bag and shake until coated evenly. Shake off the excess, transfer to a plate and set aside.
Saute: Heat the olive oil in a skillet over medium-high heat. Brown the chicken, about 2 to 3 minutes per side. Transfer to a clean plate and set aside.
Simmer: To the same skillet, add the butter. Sauté the mushrooms and the shallots, stirring occasionally, for about 3 to 4 minutes or until golden brown. Add the Marsala wine and simmer for 1 to 2 minutes, scraping up the brown bits from the bottom of the pan. Add the chicken stock and return the chicken breasts to the skillet. Lower the heat to medium and continue to simmer until chicken is cooked through, about 2 to 3 minutes. Chicken is done when it feels firm to the touch and a meat thermometer inserted in the center reaches 170 degrees F. Season sauce with remaining salt and pepper.
Finish: Transfer chicken to a platter. Swirl in the mascarpone or sour cream, balsamic vinegar, salt and pepper. Pour sauce over chicken and garnish with chopped chives. Serve with wide noodles.