- 225g/8oz butter
- 140g/5oz caster sugar
- 1 free-range egg yolk
- 2 tsp vanilla extract
- 250g/9oz plain flour
- 25g/1oz cocoa powder
- pinch salt
- 100g/3½oz dark chocolate, finely chopped
- 200g/7oz dark chocolate (at least 70% cocoa solids), finely chopped
- 200g/7oz milk chocolate, finely chopped
- 200g/7oz white chocolate, finely chopped
- Preheat oven to 190C/375F/Gas 5. Line a baking tray with baking parchment.
- With a handheld electric mixer, beat together the sugar and butter in a large mixing bowl. Beat in the egg and the vanilla extract.
- In another bowl, sift together the flour, cocoa and salt. Stir into the butter mixture, then stir in the chopped chocolate.
- Roll teaspoonfuls of dough into balls and place on the lined baking tray at least 2.5cm/1in apart. Flatten slightly with the back of spoon.
- Bake the biscuits for 10 minutes. Allow to cool for a minute on the tray, then transfer to a wire rack to cool completely.
- Meanwhile, melt the three types of chocolate separately in a microwave (at least a minute). Alternatively, melt the chopped chocolate in a bowl suspended over a pan of simmering water (do not allow the bottom of the bowl to touch the water).
- Dip the cooled biscuits halfway into one type of chocolate, then allow the excess to run off before placing on a sheet of baking parchment to set.