Dough - 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.
3.Stop, scrape down the sides of the bowl, and add the add the flour, baking soda, cream of tartar, optional salt, and beat on low speed until just combined, about 1 minute.
4.Using a medium 2-inch cookie scoop or your hands, form approximately 14 equal-sized mounds of dough (2 heaping tablespoons each), roll into balls, and flatten slightly.
6.Preheat oven to 350F, line a baking sheet with a Silpat or spray with cooking spray.
7.For Rolling - In a small bowl, combine sugar, cinnamon, and stir to combine.
8.Dredge each mound of dough through cinnamon-sugar.
9.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. I let them cool on the baking sheet and don't use a rack.
10.Cookies will keep airtight at room temperature for up to 1 week or in the freezer for up to 6 months. Alternatively, unbaked cookie dough can be stored in an airtight container 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.