1. Prepare the Bananas: Start by peeling the bananas and slicing them in half lengthwise. This shape exposes more surface area for caramelization.

2. Mix Sugar and Spices: In a small bowl, combine the brown sugar with the optional cinnamon. This mixture will create the caramelization on the bananas.

3. Preheat the Air Fryer: Set your air fryer to 375°F (190°C). Preheating ensures the bananas start cooking immediately for an even caramelization.

4. Butter the Bananas: Brush the banana slices with melted butter using a silicone brush. Make sure all sides are coated well to enrich the flavor and assist the sugar to adhere.

5. Apply the Sugar Mixture: Sprinkle the sugar and cinnamon mixture evenly over the buttered bananas. If using, sprinkle chocolate chips at this stage.

6. Arrange in the Air Fryer: Place the banana slices in a single layer on a baking pan suitable for your air fryer or lined with air fryer parchment liners. Avoid overlapping to ensure even cooking.

7. Cook: Air fry the bananas at 375°F (190°C) for about 8-10 minutes. The exact time might vary slightly depending on the air fryer model.

8. Check for Doneness: The bananas should be golden and caramelized on the outside. If they need more color, add an extra minute or two.

9. Serve Immediately: Serve these warm, caramelized bananas as is, or as a topping for ice cream, pancakes, or waffles for extra indulgence.