Preheat the oven to 400.
Lay the bananas in the foil envelope. Scrape the vanilla bean and spread the insides over the bananas. Place the scraped pod in the envelope. Add the butter, rum, sugars, and spices to the envelope, seal, and place in the oven. Bake for 8 to 10 minutes.
Remove from the oven, open the envelope and pour the banana with its sauce over the banana rum ice cream. Garnish with whipped cream, powdered sugar and mint.