In a 4- or 5-qt. slow cooker, combine mushrooms, shallots, olive oil and thyme. Add 1/4 cup Marsala wine. Cook, covered, on low about 4 hours, until vegetables are tender., Stir in sour cream, flour, lemon zest, salt and remaining Marsala. Cook, covered, on low 15 minutes longer. Sprinkle with goat cheese and parsley. Serve with hot cooked barley.