Beat butter, brown sugar, white sugar and egg until light and fluffy, about 3 minutes. Beat in hot water and vanilla. Gradually beat in flour, bicarb soda and salt until well blended and smooth. Stir in chocolate chips.
Drop dough by well-rounded teaspoons onto greased baking trays. Bake at 190 degrees C for 10 minute or until golden. Cool baking tray on a wire rack for 1 minute then remove biscuits to a rack to cool completely.