Slice each piece of bread into 3 equal sticks, about 1 inch wide. Stale bread works better here - if yours is fresh, leave the slices out on a counter for 30 minutes or give them a quick 2-minute toast in the oven to dry slightly.

In a shallow dish, whisk together the eggs, milk, vanilla, cinnamon, and granulated sugar until completely smooth. The cinnamon tends to clump, so whisk vigorously.

Preheat your air fryer to 375°F for 3 minutes. Lightly coat the basket with cooking spray.

Working in batches, dip 4-5 sticks into the custard for about 3 seconds per side - just enough to coat without soaking through. Let excess drip off, then place in a single layer in the air fryer basket. Do not overcrowd; you will need to cook in 2-3 batches.

Air fry at 375°F for 4 minutes. The sticks should look puffed and slightly set on top.

Brush the tops lightly with melted butter, then flip each stick. Brush the other side with butter. Continue air frying for 3-4 minutes until deep golden brown and crisp at the edges. Transfer to a plate and repeat with remaining sticks.

Dust with powdered sugar if desired and serve immediately with warm maple syrup for dipping.