Royal icing is a go-to building material for cake decorators, as it’s indispensable for detail-y bits like beadwork on wedding cakes. It pipes extremely well and sets up quickly into very firm and stable structures. That virtue is also royal icing’s curse, at least when it’s applied to something like a cupcake, since it dries into a very brittle coating that shatters when it’s bitten into. Even so, it’s one of those standard tools of the trade that every good baker should know how to make. Start by assembling your ingredients. Next, put your egg whites and lemon juice into the bowl of a mixer fitted with a whip. If you like you can dribble in a little bit of some sort of extract as well…vanilla, lemon or almond.
Whip for about 30 seconds until the mixture is frothy…
…then with the machine running, start adding the powdered sugar.
Whip about five minutes until it’s thick and glossy, like so:
Since exposure to air will start drying the icing out almost immediately, you’ll want to transfer this to a pastry bag or other airtight container immediately.