Preheat the oven to 150 degrees C. Grease baking trays. Stir together the flour, bicarb soda, salt and oats; set aside.
In a medium bowl, cream together the butter and brown sugar until smooth. Beat in the eggs one at a time then stir in the vanilla. Mix in the dry ingredients until well blended before stirring in the chocolate chips. Drop by heaping spoonfuls onto the prepared baking tray at least 8cm apart. Flatten biscuits to 1cm thick.
Bake for 20 minutes in the preheated oven until lightly browned. Allow biscuits to cool on baking tray for 5 minutes before removing to a wire rack to cool completely.