Cream the butter with the brown sugar and granulated sugar together well. Beat in the egg and the vanilla.

In a separate bowl, sift the flour with the cornstarch, baking soda, cinnamon and salt. Add this to the butter mixture and stir until blended. Stir in the chocolate chips.

Chill the cookie dough for at least an hour.

Preheat the oven to 165ºC. Using a small ice cream scoop or a teaspoon, scoop spoonfuls of dough (about 2 Tsp) shape them into a ball and place onto a parchment lined baking tray.

Bake for 15-18 minutes, until browned around the edges. Cool the cookies on the baking tray. If baking cookie dough that has been frozen, arrange the frozen cookies on the baking tray and let them thaw for 20 minutes at room temperature before baking as above.