Subscribe and receive a 4L Casserole Dish
Plus, save 42% on your magazine subscription
Preheat the oven to 180C/gas 4/fan 160C. Grease the base and sides of 2 shallow 28cm x 18cm baking tins and line each with a single sheet of greaseproof paper to come well above the rim of the tin (this makes it easy to lift out). Grease the paper.
Pack half the dough into the base of each tin, pressing it into the corners. Scatter with the whole nuts, making sure they are evenly distributed. Press them deeply into the dough to secure.
Bake for 40 minutes until the nuts and edges of the biscuits are golden. Carefully lift out of the tins, still on the paper, and transfer to a wire rack to cool.
Melt the plain and milk chocolates in separate bowls set over pans of simmering water. Leaving the slabs of biscuit on the paper, carefully cut each slab widthways into 2cm/¾in slices (don't worry if the nuts seem to be loose - they will be kept in place by the melted chocolate).
Spread the slices so they are 1-2cm apart and drizzle diagonal lines of melted plain chocolate over them, using a dessert spoon. Then drizzle the milk chocolate over the plain and leave in a cool place to set. Cut each biscuit in half widthways. They will keep fresh for up to a week stored in an airtight tin.