Preheat the oven to 350 degrees F. Line a baking sheet with parchment paper.
Cut each slice of bread into three "sticks". In a medium mixing bowl, whisk together the milk, eggs, vanilla, cinnamon and salt. Whisk in the apple butter.
One at a time, dip each bread stick into the egg mixture and toss to coat. Remove, allowing any excess to drip off back into the bowl. Place on the prepared baking sheet. Repeat with the remaining bread. Brush each french toast stick with a little butter (or a few small pats around the sticks). Sprinkle lightly with cinnamon sugar. Bake for 15-10 minutes, or until lightly golden, flipping halfway through baking.
Serve warm with maple syrup.
*If you cannot find apple butter or prefer to not use it, it can be omitted from the recipe.