Pre-heat oven to 180 degrees celsius, fan-forced.
Cream butter (pre-softened by leaving out of fridge for at least 1/2 and hour) and sugars (apart from cinnamon sugar which is for rolling balls in before cooking) by mixing on low speed for one minute, medium speed for one minute and high speed for two minutes.
Add eggs and vanilla and beat for another minute.
Sift flour, salt, cream of tartar and bicarb soda together and then gradually add to mixture, mixing on lowest speed or folding through with a spatula to combine.
Chill mixture in fridge for 10-15 minutes.
While mixture is chilling, make the cinnamon sugar by mixing the sugar and cinnamon together in a small bowl.
Roll tablespoons of mixture into balls and roll in the cinnamon sugar. Place on baking tray, leaving plenty of room for cookies to spread as they cook.
Cook for 10-12 minutes or until a light golden colour.
Remove from oven and allow to cool on trays for 10 minutes before transferring to a cooling rack.
Once completely cooled, store in an airtight container.