Preheat your air fryer to 350°F.
In a small bowl, mix together the sugar and cinnamon until well combined.
Spread the softened butter evenly over each slice of bread.
Sprinkle the cinnamon sugar mixture generously over the buttered side.
Place the bread slices in a single layer in the air fryer basket.
Air fry for 4-6 minutes, or until the edges are crispy and the sugar has caramelized.
Serve warm and enjoy!