Snickerdoodle Bars

0 Preheat the oven to 400°F. Line a 9”x9” metal baking pan with parchment paper, and spritz with nonstick baking spray. Set aside.
1 In a medium bowl, stir together the flour, cream of tartar, baking soda and kosher salt. (These are your dry ingredients.) Set aside.
2 In another bowl, cream together the softened butter, ¾ cup granulated sugar and the egg with a hand mixer (or a stand mixer) until light and fluffy.
3 Sprinkle the dry ingredients into the wet ingredients, mixing until just combined.
4 Using your hands, press the cookie batter into the prepared baking pan.
5 Once the batter is evenly spread throughout the pan, sprinkle the mixture of cinnamon and the remaining 1 ½ tablespoons of sugar on top.
6 Bake in the preheated oven for 18-20 minutes, or until an inserted toothpick comes out clean.
7 Let cool for 20-30 minutes before slicing and enjoying.