Preheat Your Oven: Begin by preheating your oven to 350°F (175°C). Line a 9x13-inch baking pan with parchment paper for easy removal of the bars later.
Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking soda, cream of tartar, and salt. Set this mixture aside for later.
Cream Butter and Sugar: In a large mixing bowl, beat together the softened butter and 1 ½ cups of sugar until light and fluffy. This should take about 2-3 minutes with a handheld mixer or stand mixer.
Add Egg and Vanilla: Beat in the egg and vanilla extract until fully incorporated. Remember, this will enhance those flavors!
Combine Dry and Wet Ingredients: Slowly add the dry ingredient mixture into the wet mixture, blending until just combined. Avoid overmixing to keep your bars tender.
Spread the Mixture: Spoon the batter into the prepared baking pan and spread it evenly.
Prepare Topping: In a small bowl, combine the ½ cup of granulated sugar and 2 tablespoons of ground cinnamon. Sprinkle this mixture evenly over the top of the cookie batter.
Bake: Bake for 20-25 minutes, or until the edges are lightly golden and a toothpick inserted in the center comes out clean. Allow to cool completely before cutting into bars.
Serve: Once cool, slice into squares and serve. Enjoy!