Preheat oven to 180 degrees C. Mix flour, bicarb soda and salt; set aside.
In a large bowl, cream together the butter and sugar until light and fluffy. Beat in the egg then stir in the vanilla. Mix in the dry ingredients until well blended. Stir in the chocolate chips and walnuts. Roll the dough into 5cm balls and place them 8cm apart on ungreased baking trays.
Bake for 20 to 23 minutes in the preheated oven. Allow biscuits to cool for a few minutes on the baking tray before removing to a wire rack to cool completely.