Many drink recipes call for superfine or caster sugar. I don’t even know where you could buy this, but here’s how to make your own.
For 1 cup of superfine sugar, measure 1 1/3 cup granulated sugar into a food processor with the blade attachment. Cover the processor with a damp dish towel because the sugar makes a fine dust. Process sugar about 1 minute, until it’s superfine. Let dust settle about 1 minute before opening the processor and there you have it! Store like you would regular sugar.