Preheat the oven to 375° and line a baking sheet with parchment paper.
In a medium sized bowl whisk together the flour, cream of tartar, baking soda and salt. Set aside.
In another medium bowl beat the butter and sugar together until pale and fluffy, about 4-5 minutes. Add in the eggs and vanilla and beat for another 2 minutes. Be sure to scrape down the sides of the bowl to make sure everything is well combined.
Add the dry ingredients in to the wet and mix until fully combined. Cover the bowl with plastic wrap and chill for 30 minutes.
While the dough chills, combine the sugar and cinnamon in a small bowl.
Form the dough into equal sized balls, about 1 inch and roll in the cinnamon sugar and coat evenly. Place the coated balls on the baking sheet keeping about 2 inches between them. Bake for 10 minutes. The cookies will look quite underbaked, but that's how they should look! Allow to cool for a few minutes on the pan before transferring to a cooling rack.