In a bowl cream butter with the sugar using an electric mixer or wooden spoon until the consistency is pale in color and well mixed.

Add Vanilla Essence/Extract together with the lemon zest and incorporate well.

Sieve the Flour and Cornstarch, add into the bowl and mix until just incorporated. Do not over mix.

Take out the dough, place onto a lighly floured surface and gather it together lightly. Separate into two batches. Add Cocoa Powder into one of the batches and mix well.

Using your hands, divide the dough into small balls and roll them between the palms of your hands. Place them on a cookie sheet and use two fingers to flatten them slightly.

Bake for 15-20 minutes at 163 Degrees Centigrade until the edges begin to brown slightly. Do not let the cookies become brown, otherwise they will become hard when they cool down. Remove from the oven and let them cool completely.Store them in an air tight container. Enjoy.