Place a rack in the center of your oven and preheat the oven to 350 degrees F. For easy clean up, line a baking sheet with aluminum foil or a silicone baking mat. Place a baking rack on top and GENEROUSLY and COMPLETELY coat the rack with nonstick cooking spray (do not skimp or the French toast will stick). In a small bowl, stir together the sugar and 2 teaspoons of the cinnamon. Cut each slice of bread lengthwise into 3 or 4 strips depending upon the size of your bread; each "stick" should be about 1-inch wide and 3/4-inch thick. In a large, shallow dish or bowl (a deep pie dish works well), add the eggs, milk, maple syrup, vanilla, zest (if using), salt, and remaining 1/4 teaspoon cinnamon. Whisk to combine. Working one at a time, dip each stick of bread into the egg mixture. Coat each stick on all sides, but do not allow it to become completely soggy. Shake off any excess, then place on the baking sheet. Repeat with the remaining sticks, ensuring that they do not touch each other on the baking sheet. Sprinkle the French toast sticks with half of the cinnamon sugar mixture. Bake the French toast sticks for 10 minutes. Remove from the oven, carefully flip, then spray lightly with cooking spray. Sprinkle the remaining cinnamon sugar over the top. Return the French toast sticks to the oven and continue baking for 10 additional minutes, or until golden and cooked through. Enjoy warm with desired toppings.