For some reason, people have gotten into the habit of thinking that in order to make a Hot Buttered Rum, you need to use a batter mix. This means either taking the time to mix it up from scratch yourself, or buying a pre-mix from the store. Either way, you will end up with far too much if all you want is a single drink. There isn't any reason why you can't mix up a Hot Buttered Rum ala minute, so why not?