On YouTube there is a channel called So Easy. Their stuff is hypnotic to watch, but I can’t for the life of me figure out what they’re using to ice with. It’s shiny, almost looks whipped, but is apparently stiff enough to make flowers with? Any ideas?

I’ve seen this type of icing on many Korean buttercream tutorials. Icing is tricky and complicated to make. Really all you really have to do is add some corn syrup and a bit of glycerin to regular butter buttercream to get that kind of gloss. It will still crust.

Thanks for the tip, June!  I had no idea.