Mix breadcrumbs and Parmesan, set aside. In a medium bowl, combine milk with egg, mixing well. Dip chicken breasts, one at a time, in milk/egg mixture and then dredge through bread crumbs, coating well. Heat oil in a large frying pan over medium/high heat. When oil is hot, cook chicken about 7 min. per side, or until golden and juices run clear and meat is white throughout. Remove to dish. While chicken is hot, top with Mozzarella. Cheese should melt slightly. Spread 1 Tbsp. Dijon Mustard in each Kangaroo Pocket Bread half. Stuff with chicken and add romaine lettuce.