1Set oven control to broil. Spray broiler pan rack with cooking spray.
2Mix egg product, milk, mustard, salt and pepper in medium bowl. Stir in bread crumbs and onion. Stir in beef. Shape mixture into 6 patties, each about 1/2 inch thick. Place patties on rack in broiler pan.
3Broil with tops of patties about 5 inches from heat 6 minutes. Turn, broil until meat thermometer inserted in center reads 160°, about 4 to 6 minutes longer. Serve patties in buns.