To cover a cake, mix the icing until it holds stiff peaks. For piping, you want it a little thinner so it flows through the nozzle. It’s best to cover the cake with marzipan first so you don’t ...
However, there are occasions when a hard set is desireable (for instance if you wish to store the cake for a long time or you want a really hard smooth set on the icing so you can pipe decorative ...