Preheat oven to 180 degrees C. Grease baking trays.
Cream together butter and icing sugar until smooth. Stir in vanilla. Mix in the flour and then one cup of the chocolate chips. Shape dough into 5x1cm logs. Place logs 5cm apart on prepared baking trays.
Bake for 10 to 13 minutes in preheated oven or until firm. Let biscuits cool completely before removing from tray (shortbread is brittle).
Melt the remaining 1 cup chocolate chips and butter in a bowl over boiling water stirring frequently until smooth.
Dip one end of each biscuits into the chocolate then into the nuts. Place onto baking paper until set.