Peel bananas, splitting lengthwise and cutting in halves. Place bananas in a buttered, shallow, oven-proof baking dish and dot with butter. Sprinkle sugar over bananas. Bake uncovered at 325'F for about 35 minutes. Set dish on stove, being careful to keep warm. Pour rum in a long-handled spoon, which has been warmed by dipping in boiling water. Set a match to the rum and as it flames pour over bananas. As it runs down in the dish, ladle it up and over the bananas until the flaming ceases. The secret of this dessert is to have all ingredients warm, otherwise it will not flame well. This old recipe, as good today as years ago, was brought to Louisiana by a distant relative of Empress Josephine, at whose table this was often served.