Prosciutto and Cheese Stuffed Lamb Tenderloin

Name: Prosciutto and Cheese Stuffed Lamb Tenderloin
Ingredients: 4 (8-ounce) boneless lamb tenderloins, see Cook's Note*; Salt and freshly ground black pepper; 4 thin slices prosciutto or ham; 4 thin slices (about 1/2-ounce each) Pecorino Romano; 8 whole fresh basil leaves; 3 tablespoons olive oil; 1/2 cup dry Marsala wine or dry sherry; 1/2 cup low-sodium chicken stock; 2 tablespoons unsalted butter, at room temperature; 2 tablespoons chopped fresh basil leaves; Special equipment: kitchen twine