Preheat grill to medium-low (300°F to 350°F).

In a small bowl, combine the brown sugar and cinnamon.

Slice the bananas in half lengthwise, leaving the peel on.

Brush the fruit side of each banana with melted butter. Sprinkle with the brown sugar mixture and let sit for five minutes.

Place the bananas peel side down on preheated grill and grill for 3 minutes. Flip the bananas and grill fruit side down for an additional 2 minutes until caramelized.