For an extra layer of flavor, consider adding a sprinkle of cinnamon or nutmeg to the custard mixture. Feel free to experiment with different types of bread, such as challah or croissants, for a unique twist. If you don't have rum on hand, you can substitute it with bourbon or brandy, or simply omit it altogether. The bread pudding can be prepared ahead of time and stored in the refrigerator overnight. Just add an extra 15-20 minutes to the baking time.