Preheat oven to 375F. Whisk the flour, baking soda, cream of tartar, salt, and cinnamon together in a large bowl.
Cream the butter in the bowl of your stand mixer fitted with a paddle attachment. Add the sugars and beat until light and fluffy.
Add eggs on at a time while mixing on low. Scrape the bowl down and mix in the vanilla
Add the flour mixture to the batter and beat on low until just combined. Scrape the down down and fold in any remaining flour.
In a medium bowl mix sugar and cinnamon together for rolling.
Use a medium ice cream scooper or tablespoon to portion out the cookie dough. You'll want enough to roll balls that are 1.5-2 inches wide.
Roll the dough in the palms of your clean hands then roll in cinnamon sugar.
Transfer to a parchment-lined baking sheet and bake at 375F until puffed and just golden, about 10 minutes. Remove from oven and allow to cool on baking sheet for 5 minutes then transfer to a wire rack to cool completely
Measure your flour correctly! Adding too much flour to the recipe is the most common mistake. The best, and easiest way to measure flour is by using a scale. If you don’t have one then fluff your flour with a spoon, sprinkle it into your measuring cup, and use a knife to level it off.
If you love cinnamon the spoon some of the cinnamon sugar over each ball of cookie dough before placing on the baking sheet. You’ll get way more cinnamon than if you just rolled them.