In mixing bowl, beat the egg whites, milk, flour, butter and salt until smooth. Pour into an 8-in square baking dish coated with nonstick cooking spray. Bake at 400 for 20-25 minutes or until golden and puffed. Meanwhile in a small saucepan, combine the apples, jelly, water and cinnamon. Heat over low heat until jelly is melted and mixutre is heated through. Cut popover into 6 pieces and serve with apple topping.