Preparation Steps

• In a stand mixer fitted with the paddle attachment, cream the unsalted butter, granulated sugar, and light brown sugar together on medium-high speed until light and fluffy, about 3 minutes.
• Add the egg and vanilla extract to the creamed mixture and beat on medium-high speed until combined and fluffy, about 3 minutes.
• Reduce the mixer speed to low and add the all-purpose flour, baking soda, cream of tartar, and salt if using. Mix until just combined, about 1 minute.
• Using a 2-inch cookie scoop or your hands, form about 14 equal-sized dough balls, flatten them slightly, and place on a large plate or tray.
• Cover the dough balls and refrigerate for at least 1 hour to chill. Do not bake unchilled dough to prevent spreading.
• Preheat the oven to 350°F (177°C) and line a baking sheet with a Silpat or spray with cooking spray.
• Mix the 0.25 cup granulated sugar with ground cinnamon in a small bowl to create the cinnamon sugar coating.
• Roll each chilled dough ball in the cinnamon sugar until fully coated.
• Place the coated dough balls on the prepared baking sheet spaced at least 2 inches apart and bake for about 9 minutes until edges are set and lightly golden but centers are still soft and glossy.
• Allow the cookies to cool on the baking sheet for about 10 minutes before transferring to a cooling rack or serving.