One to impress - these are no shop-bought gems
- Preheat the oven to 180°C.
- Put the flour into a large mixing bowl and stir in the sugar. Rub in the butter until the mixture resembles breadcrumbs. Add the egg yolk and draw the mixture together to form a smooth, soft dough.
- Roll the dough out into a large rectangle about 3mm thick. Cut out tiny circles using the cookie cutter. Bring the trimmed dough together and roll out again to cut as many cookies out of the dough as possible. Arrange on the baking sheets.
- Bake in the preheated oven for about four minutes, until golden and firm. Leave to cool on the baking sheet.
- Meanwhile, whisk the egg white until light and add the icing sugar. Mix until very thick and smooth. Divide the mixture into two or three batches and colour each with a little colouring gel.
- Spoon the icing into the piping bags and pipe a little rosette on the top of each cookie. Leave to dry for a couple of hours. Store between layers of parchment in an airtight container and eat within three days.