Combine butter, sugar and cinnamon in a pan or skillet. Place over low heat stirring until sugar dissolves. Stir in banana liqueur, then place bananas in pan. When bananas soften and begin to brown, carefully add rum. Continue to cook sauce until rum is hot, then tip pan slightly to ignite rum. When flames subside, lift bananas out of pan and place 4 pieces over each portion of ice cream. Generously spoon warm sauce over top of ice cream and serve immediately.