In a small skillet over medium heat, melt the butter.
Add the brown sugar and cinnamon, stirring until the mixture is bubbly and well combined.
Slice the banana in half lengthwise and place it cut-side down in the skillet.
Cook for about 1-2 minutes until the banana is caramelized, then carefully flip it over.
Add the dark rum and let it cook for another minute, allowing the alcohol to cook off.
Remove from heat.
Serve the caramelized banana over a scoop of vanilla ice cream, drizzling the sauce from the skillet on top.
Enjoy immediately.