Combine the egg substitute, milk, cinnamon, and vanilla extract in a shallow bowl, and stir to mix well. Dip each slice of bread in the egg mixture, turning to coat both sides.
Coat a griddle or large skillet with nonstick cooking spray, and preheat over medium heat until a drop of water sizzles when it hits the heated surface. (If using an electric griddle, heat the griddle according to the manufacturer's directions.)
Lay the bread slices on the griddle and cook for about 2 minutes on each side or until golden brown. As the slices are done, transfer them to a serving plate and keep warm in a preheated oven.
Serve hot, either plain or topped with maple syrup.