1. To the bowl of a stand mixer fitted with the paddle attachment (or large mixing bowl and electric mixer) combine the butter, sugars, and beat on medium-high speed until creamed and well combined, about 3 minutes
2. Stop, scrape down the sides of the bowl, and add the egg, vanilla, and beat on medium-high speed until well combined, light and fluffy, about 3 minutes. Stop, scrape down the sides of the bowl, and add the add the flour, baking soda, cream of tartar, salt, and beat on low speed until just combined, about 1 minute.  Chill dough for at least 1 hour. ( If you don’t chill the dough, the cookies will bake thinner, flatter, and be more prone to spreading.)  Roll approximately 2 Tablespoons of dough into balls, and flatten slightly. . Preheat oven to 350F, line a baking sheet with a Silpat, parchment paper or spray with cooking spray.

For Rolling – In a small bowl, combine sugar, cinnamon, and stir to combine.

1. Drop and roll each mound of dough through cinnamon-sugar. Place dough mounds on baking sheet, spaced at least 2 inches apart (I bake 8 cookies per sheet) and bake for about 9 minutes, or until edges have set and tops are just set, even if slightly undercooked, pale, and glossy in the center; don’t overbake for soft, pillowy cookies. For firmer cookies, bake a minute or two longer. Cookies firm up as they cool. Allow cookies to cool on baking sheet for about 10 minutes before serving.
2. I like to keep unbaked cookie dough in the refrigerator for up to 5 days, or in the freezer for up to 4 months, so consider baking only as many cookies as desired and save the remaining dough to be baked in the future when desired.