The way you measure your flour is key in this iconic cookie recipe. In Food Network Kitchens, we spoon flour into the measuring cup and level it off with a knife. We find this to be a more accurate way to measure than scooping.
Adjust oven rack to the middle position and preheat oven to 400 degrees F. Whisk together the flour, baking soda, cream of tartar and 1/4 teaspoon salt in a medium bowl.
Add the butter, 1 cup of the granulated sugar, brown sugar and egg to the bowl of a stand mixer fitted with a paddle attachment (or a large bowl if using a hand mixer). Beat on medium speed just to combine, about 30 seconds. Add the flour mixture in 2 parts and beat on low until just combined. Let the dough rest at room temperature for 30 minutes.
Whisk together the remaining 1/4 cup granulated sugar and cinnamon in a small bowl.
Form the dough into 1 1/4-inch balls (about 1 tablespoon dough per cookie). Roll each ball in the cinnamon-sugar and coat well; arrange on two baking sheets, 2 inches apart. Do not flatten the balls, as they will spread a lot in the oven.
Bake one sheet of cookies at a time until the tops look cracked and the center still feels soft, about 9 minutes. Let the cookies cool in the pan for 3 minutes; they will continue cooking during this time. Once they've firmed up a little, transfer them to a rack to continue cooling. Store the cooled cookies in an airtight container for up to 3 days.
Copyright 2013 Television Food Network, G.P. All rights reserved