I only made the ghosts so I can’t speak to both varieties, but they came out pretty well. The trick is to make your little rounds of cake small enough so you don’t have to put a giant heap of buttercream (or frosting) on top to make their little pointy heads. Here’s where you’ll thank your lucky stars for your biscuit cutter set (and if you don’t have one, order it now!!). Not being an expert icing piper, I have to say the points gave me a little trouble, but the nice thing about a glaze is that it covers a lot of mistakes, especially when applied in more than one layer. And on that note, do indeed refrigerate any petit four (Halloween or otherwise) before you apply your sugar glaze. Giving your buttercream time to firm up will keep your cakes from falling apart. This is especially true of layered petits fours, which can be ever-so-delicate.
Lastly, while I like sugar glazed petits fours, they can be a little sweet. Especially when they’re made with fondant (which is part fructose, and hence a lot sweeter tasting than regular sugar) they can really curl your teeth. My alternative of choice is a thin coating of white chocolate, which you can simply melt down in your microwave and use as you would a sugar glaze. It’s a more opaque, more forgiving and more flavorful top coat. And what’s not to love about that?