Preheat oven to 350 degrees.
In a bowl, whisk the butter and sugar (preferably with a hand mixer) until light and fluffy (~5 mins). Add in the eggs and vanilla extract and mix for another couple of minutes.
In a separate bowl, combine the flour (sifted, preferably), cream of tartar, baking soda and salt.
Add the flour mixture to the first bowl and stir to combine until you have a well formed dough.
Cover the bowl and let the dough rest in the fridge for 20-30 minutes.
In a small bowl, combine some extra sugar and cinnamon.
Once rested, take the dough and make small balls by rolling it into your palm (1-2 tablespoons of dough depending on cookie size you want). Roll you dough ball in the cinnamon-sugar mixture until completely coated. Drop the coated ball onto a greased cookie sheet (or parchment paper) and flatten it with your hand or a fork to form a round disc. Repeat until your cookie sheet is filled.
Bake for 9-11 minutes. Let cool for a few minutes on baking sheet until they are firm enough for you to move them to a cookie drying rack. You can optionally add sprinkles for an extra touch.