** The cookies may look a little large in the picture - that's my fault. I'm HORRIBLE at judging how big of a cookie dough ball I'm making - I ALWAYS make them too big!**
Source: Cook's Illustrated, via The Way the Cookie Crumbles, via Annie's Eats
Makes about 30 cookies
2¼ cups (11¼ ounces) unbleached all-purpose flour
2 teaspoon cream of tartar
1 teaspoon baking soda
½ teaspoon salt
12 tablespoon unsalted butter, softened but still cool
¼ cup vegetable shortening
1½ cups (10½ ounces) granulated sugar, plus 3 tablespoon for rolling dough
2 large eggs
1 tablespoon ground cinnamon, for rolling dough
1. Adjust oven racks to upper- and lower-middle positions. Preheat the oven to 400ºF. Line baking sheets with parchment paper. In a medium bowl, whisk together the flour, cream of tartar, baking soda and salt; set aside. In the bowl of an electric mixer fitted with the paddle attachment, cream the butter, shortening and 1½ cups sugar on medium speed until well combined, 1 to 1½ minutes. Scrape down the sides of the bowl, add the eggs, and beat again until combined, about 30 seconds. Add in the dry ingredients and beat at low speed until just combined, about 20 seconds.
2. In a small, shallow bowl, combine the 3 tablespoons sugar and the cinnamon for rolling the dough. Stir or shake well to combine. Working with a heaping tablespoon of dough each time, roll the dough into 1½-inch balls. Roll the balls in the cinnamon sugar mixture and place them on the prepared baking sheets, about 2 inches apart. Use a drinking glass with a flat bottom to gently flatten the dough balls to ¾-inch thickness (butter the bottom of the glass before starting, and dip it in sugar between cookies if it begins to stick).
3. Bake until the edges of the cookies are beginning to set and the center are soft and puffy, 9-11 minutes, rotating the baking sheets front to back and top to bottom halfway through the baking time. Let the cookies cool on the baking sheets 2-3 minutes before transferring them to a wire rack to cool completely.