If you use an electric beater to make the icing, so much the better; otherwise wait until you feel energetic and use a good-sized bowl and a wooden spoon. It will take 5–10 minutes of steady mixing but you will be pleased with the result. Royal icing can be so hard that it’s difficult to eat unless an emulsifier is added in the form of glycerine or honey. So my recipe includes this. But if you prefer a rock-like icing, leave out the glycerine.