In a large bowl, stir together the butter, white sugar and brown sugar until smooth. Mix in eggs one at a time, then stir in the vanilla. Combine the flour, bicarb soda and salt; stir into the batter just until blended then mix in the chocolate chips so they are evenly distributed. Drop biscuits by heaping teaspoonfuls onto ungreased baking trays spacing 5cm apart.
Bake in the preheated oven until the edges begin to turn golden, 12 to 15 minutes. Allow biscuits to cool for a few minutes on the baking trays before removing to wire racks to cool completely.
For firmer biscuits:
If you like firmer biscuits, increase the flour by 1/4 cup.