1. In a small bowl, mix sugar and cinnamon. Stir to combine and set aside.
2 Mix flour, baking soda, cream of tarter and salt with fork and set aside.
3. In the bowl of a stand up mixer with the paddle attachment mix butter. Add sugars and beat on medium-high speed until well combined (about 3 minutes).
4 Stop the mixer, scrape down the sides of the bowl. Turn mixer on low speed, add the eggs and vanilla. Beat on medium high speed until well combined, light and fluffy.
5. Stop the mixer, scrape down the sides of the bowl. Turn mixer on low speed and add the flour mixture until just combined (about 1 minute).
6. Put bowl in refrigerator to chill for 15-30 minutes. Once dough has firmed up slightly,, use a Tbsp cookie scoop or a spoon and your hands to form balls of dough. Place the balls of dough on parchment lined cookie sheets. Cover with plastic wrap and place cookie sheet in refrigerator to chill for a couple of hours or put dough balls in an airtight container for up to 5 days.
DOUGH MUST CHILL!!
7. Preheat oven to 350º and line 2 baking sheets with Silpat or parchment paper.
8. Take 10 (or however many dough balls will fit on baking sheet) out of the refrigerator. Make an indent in the top of each dough ball. Dredge the balls in the cinnamon-sugar mixture, letting the cinnamon/sugar pool in the indent at the top of the dough ball.
9. Place dough balls on baking sheet, allowing space for cookies to spread. Bake for about 9 minutes and 15 seconds or until edges have set and tops are just set, even if slightly undercooked, pale and glossy in the center, do not over bake. Cookies firm up as they cool. Allow cookies to coo. on baking sheet for about 6 minutes. Don't use a cooking rack.