Saute butter, sugar and pineapple chunks for 10 minutes in a saucepan. Add orange juice and cinnamon, bring to a boil. Dilute cornstarch with two tablespoons water, add to sauce. Reduce heat and let simmer for three minutes. Add bananas, simmer for two minutes, turn heat off.
Divide half the banana mixture among the pineapple shells and top each with one scoop vanilla ice cream. Pour the remaining sauce mixture on top of the ice cream and then the rum, and light the rum with a flame.