Beat butter, sugar and vanilla together until creamy.
Add corn starch paste and beat until creamy, don't worry if it curdles slightly.
In another bowl, sieve all flour, baking soda and salt together and mix with a whisk.
Add flour mix to butter mix, and using your hands mix together to form a soft dough. If it's sticking to your fingers add more flour until it forms a soft dough ball.
Cover and leave in fridge for at least an hour or even over night.
Pre heat your oven to 180C/356F. Grease and line 1 large baking tray with baking paper.
Remove dough from fridge and flour a clean surface
Roll dough to 1.5CM thick and cut out 6 cookies using a large cookie cutter. See video for tips on how to get perfectly shaped cookies.
Bake in preheated oven for 10-12 mins or until tops are just firm and cookie is slightly golden brown. Remove from oven and leave to cool down.