Preheat oven to 180° C. Line a baking tray with a silicon sheet.
Sift together flour, baking soda, cream of tartar, salt and 1 teaspoon cinnamon powder in a bowl.
Beat together butter, ⅓ cup castor sugar and brown sugar in a planetary mixer till light and fluffy.
Add egg, egg yolk and vanilla essence; beat for another minute, scraping the sides as and when necessary. Add the sifted flour mixture.Mix well.
Mix together ½ tablespoon cinnamon powder with ½ tablespoon castor sugar in a plate till well combined.
Divide the dough into 16 equal portions and shape them into balls. Roll them in the cinnamon-sugar mixture.
Place them on the baking tray, place the tray in the preheated oven and bake for 10-12 minutes or till they turn light golden. Remove from heat and cool.