Melt butter over an alcohol burner in a flambe pan or attractive skillet.
Add the sugar, cinnamon, and banana liqueur and stir to mix. Heat for a few minutes.
Place the halved bananas in the sauce and sauté until soft and slightly browned.
Add the rum and allow it to heat well, and then tip the pan so that the flame from the burner causes the sauce to light. Wait until the rum gets hot, so that you get a good flame after its ignited. Allow the sauce to flame until it dies out, tipping the pan with a circular motion to prolong the flaming.
Carefully lift the bananas out of the pan and place four pieces over each portion of ice cream, and then spoon the hot sauce from the pan over the top.