Icing & frosting

How to tell it is going right

• The temperatures were chosen, not defaulted: the bake fully cool where the finish is meant to sit on top of it, or both deliberately warm where the method wants the two to fuse, and the proof either way is a finish that stayed where it was put.
• Smooth on the tongue: no grit of undissolved sugar and no lumps of anything that was never fully worked in.
• The consistency matches the job: it spreads or pours the way the method intends, then holds the edge, swirl, or drip it was given.
• The surface underneath is intact: covered rather than scrubbed, with no crumbs dragged through the finish and no torn patches showing.
• By serving it has settled into the finish the method wants (matte, glossy, or soft) and a cut comes away clean rather than pulling the top off with it.

Where it goes wrong A finish meant to sit on top went on while the bake was still warm. The layer that touched first melted, slid, and soaked in; what is left sets greasy and streaked, and no amount of chilling afterwards puts that finish back.