Preheat the oven to 190C/375F/Gas 5.
Rub together the flour, caster sugar and margarine until it begins to come together as a dough. Add a little bit more flour if the mix seems too wet.
Mix in the chocolate chunks and nuts.
Shape the dough out into a long sausage shape on a board, and cut into rounds about 1cm/½in wide. Because of the chocolate and nuts in the mixture it may be quite crumbly.
Grease and flour a non-stick baking tray. Place each round on the tray and gently press each down with the back of a fork.
Bake at the top of the oven for 15 minutes, or until golden brown. Leave to cool for at least ten minutes before putting on a wire rack.
