Melt butter in a 10-inch heavy skillet over low heat. Add brown sugar, allspice and nutmeg and stir until sugar dissolves. Add banana liqueur and bring sauce to simmer. Add bananas and cook for 1 minute on each side, carefully spooning sauce over bananas as they are cooking. Remove bananas from pan to a serving dish. Bring sauce to a simmer and carefully add the rum. If the sauce is very hot, the alcohol will flame on its own. If not, using stick flame, carefully ignite and continue cooking until flame dies out, approximately 1 to 2 minutes. If sauce is too thin, cook for 1 to 2 minutes until it is syrupy in consistency. Add orange zest and stir to combine. Immediately spoon the sauce over bananas and serve. Serve with waffles, crepes, or ice cream.
Use extreme caution when igniting alcohol. Remove the pan from the heat source before adding the alcohol. Pour the alcohol into the pan and carefully ignite with a match or click lighter. Return the pan to the heat and gently swirl to reduce the flames.