Place the biscotti in a large zip-top plastic bag, coarsely crushing them with a meat mallet or rolling pin to yield 1/2 cup; set aside.
Place the fudge sauce in a microwave-safe bowl. Cover and microwave on high 45 seconds or until melted.
Spoon 1/4 cup ice cream into each of the 8 parfait glasses. Top the ice cream with 1/4 cup banana and 1 tablespoon whipped cream; repeat the layers, ending with the whipped cream. Sprinkle each parfait with about 1 tablespoon biscotti crumbs, and top with about 1 1/2 teaspoons fudge sauce.