Depending on the size of you cupcakes, if you whipped up any butter and frosted the bomb, it might be too much butter, too greasy in the water. Maybe a mixture of mp and some cocoa butter, whipped. Are these made commercially? If so, get your hands on one, it may say on the packaging. You may be able to kinda figure it out just by feel. Is it soft, hard, dry and flaky, oily etc.