Ingredients
1 1/2 pounds boneless skinless chicken breasts, each breast cut crosswise into 3 pieces
Salt and freshly ground black pepper
2 tablespoons olive oil
5 tablespoons butter, divided
3/4 cup chopped onion
1 pound cremini mushrooms, sliced
2 tablespoons minced garlic
1 cup dry Marsala wine
1 cup (8 ounces) mascarpone cheese
2 tablespoons Dijon mustard
2 tablespoons chopped fresh Italian parsley leaves, plus whole sprigs, for garnish
12 ounces dried fettuccine