Heat a medium skillet over medium heat. Add 1/3 cup panko to the pan, and cook for 2 minutes or until toasted, stirring frequently. Remove from heat, and place the panko in a shallow dish.
Cut mozzarella sticks into 1-inch pieces. Working with one piece at a time, dip the cheese in egg substitute; dredge in panko. Place cheese on a baking sheet coated with cooking spray. Bake at 425° for 3 minutes or until the cheese is softened and thoroughly heated.
Heat marinara sauce until thoroughly heated, stirring often. Serve with mozzarella pieces.