1/2 cup unsalted butter, softened
1/2 cup granulated sugar
1/3 cup light brown sugar, packed
1 large egg
1 teaspoon vanilla extract
1 1/2 cups all-purpose flour
1/2 teaspoon baking soda
1/4 teaspoon cream of tartar
1/4 teaspoon salt, optional and to taste
1/4 cup granulated sugar
2 teaspoons cinnamon
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.
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, optional salt, and beat on low speed until just combined, about 1 minute.
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.
Preheat oven to 350F, line a baking sheet with a Silpat or spray with cooking spray.
For Rolling - In a small bowl, combine sugar, cinnamon, and stir to combine.
Dredge 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. I let them cool on the baking sheet and don’t use a rack.
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.