Caster sugar

Caster sugar is white sugar with smaller crystals than ordinary granulated sugar. It is the standard sugar in British baking. In the US it is sold as superfine sugar, and sometimes as baker's sugar.

The finer grain dissolves faster, which matters in a few places. Creamed with butter for a sponge, it makes a lighter, more even crumb. Whisked into egg whites for meringue, it dissolves before the meringue sets, so the result isn't gritty or weeping. It also sweetens cold drinks, fruit and whipped cream without a crunch.

Golden caster sugar is the unrefined version, with a pale colour and a faint caramel note. It can usually be used in place of white, though meringues come out slightly beige.

Don't confuse it with icing sugar, the powdery kind for icing, which Americans call powdered or confectioners' sugar.

If you have no caster sugar, blitz granulated sugar in a food processor or spice grinder for a few seconds. In most cakes plain granulated works too, with a slightly coarser texture.