Cut the bananas lengthwise, then across. Melt the butter in a deep skillet on high heat on the stove until it begins to foam. Place the bananas with the cut side down, and sauté them lightly, shaking the skillet gently for about 1 minute.
Remove the skillet from the heat and pour the sugar and rum around the bananas. Return the skillet to the heat once more and continue to fry until the sugar melts, still shaking occasionally to cover the bananas with the mixture. Then add spices and lower the heat.