Directions

Preheat the oven to 400°F, with one rack in top third and one rack in bottom third of oven. Line baking sheets with silicone baking mats or parchment paper; set aside.

Sift together flour, cream of tartar, baking soda, and salt; set aside. In the bowl of an electric mixer fitted with a paddle attachment, combine butter and 300 grams of sugar. Beat on medium speed until light and fluffy, about 2 minutes. Scrape down sides of bowl. Add eggs, and beat to combine. Add dry ingredients, and beat to combine. Chill the dough for an hour before scooping it.

Once dough has chilled, in a small bowl, combine remaining 50 grams sugar and the ground cinnamon. Use a small ice-cream scoop to form balls of the dough, and roll in cinnamon sugar. Place about two inches apart on the prepared baking sheets. Bake until the cookies are set in center and begin to crack, about 10 minutes, rotating the baking sheets after five minutes. Transfer the sheets to a wire rack to cool about five minutes before transferring the cookies to the rack.