Cream together the butter, caster sugar and brown
sugar until smooth. Beat in the eggs one at a time,
then stir in the vanilla. Dissolve bicarbonate of soda in
hot water. Add to batter along with salt. Stir in flour,
chopped Mars bars and nuts (optional). Drop by large spoonfuls onto ungreased baking trays.
Bake for about 10 minutes in the preheated oven,
or until edges are nicely browned.
Instead of putting the Mars bars you can put 250g of chocolate chips of your choice.