Photograph: Dan Jones
In a food processor, blitz the Brazil nuts. Add the flour, caster sugar and butter and pulse to a large crumb texture.
Turn out and work together until you have a dough. Form the dough into a disk and wrap in clingfilm. Chill for 30 minutes.
Roll the dough to about 5mm thick between 2 sheets of baking paper (this makes it easier). Stamp out stars with a 5cm star cutter – you'll need to do this in batches. You want about 35 stars in total.
Transfer the stars to baking sheets lined with baking paper. Pop into the freezer for about 20 minutes. Preheat the oven to 180°C, fan 160°C, gas mark 4.
Bake for 12-15 minutes or until golden.
Leave to cool completely before transferring to wire racks.
Pour the melted chocolate into separate piping bags. Drizzle vertical lines with the dark chocolate, leave to set slightly, then drizzle the opposite way with the white chocolate.
If you prefer, drizzle the chocolate with a teaspoon. Leave to set completely.
Get ahead: make a few days ahead and store in an airtight container. Or freeze the dough stars and bake from frozen