Preheat oven to 325 degrees C
Line baking sheets with parchment paper
In a small bowl whisk together the flour, cream of tartar, baking soda, and salt. Set aside
In a large mixing bowl, cream butter and both sugars using a stand mixer. Mix on medium to high speed for 3-4 minutes, or until light and fluffy
Scrape the butter and sugar from the sides and bottom of the bowl and add the eggs one at a time and mix until combined. Add the vanilla and cream for 1-2 minutes
With the mixer on low add the flour mixture. Mix on the lowest speed setting until just combined.
In a small bowl, stir together sugar and cinnamon for the coating.
Using a smaller cookie scoop, about 2 tbsp, scoop balls of dough and drop them into the coating. Gently roll the balls until smooth and fully coated with cinnamon & sugar.
Place on baking sheets and bake for 9-11 minutes. Let cool for several minutes before removing from the pan and onto a cooling rack.