These snickerdoodle cookie bars have a soft & chewy texture, delicious butter flavor, and a crunchy layer of cinnamon sugar. These are way easier than making snickerdoodle cookies, and you don't have to chill the cookie dough!
Preheat the oven to 350F degrees. Line an 8x8 (20x20 cm) pan with parchment paper, leaving an overhang around the edges. I recommend lightly greasing the pan first to keep the paper in place. Alternatively, simply lightly grease the pan.
In a small bowl, whisk together the ingredients for the cinnamon sugar topping - ¼ cup granulated sugar, 1 tablespoon cinnamon and ¼ teaspoon ground nutmeg. Set aside.
In a large bowl whisk together the melted butter, ½ cup granulated sugar and ¼ cup brown sugar until you no longer see pools of melted butter.
Whisk in the egg and vanilla extract.
In a separate small/medium bowl, whisk together the flour, cornstarch, cream of tartar and salt.
Whisk the dry ingredients into the butter mixture until there are no lumps of flour. You can do this with a wire whisk, or an electric mixer works too.
Spoon the dough into the prepared pan and smooth into an even layer.
Sprinkle the cinnamon sugar mixture on top into an even layer. I use it all for a thick crunch, but feel free to use not all of it if you want less cinnamon sugar.
Bake in the middle of the preheated oven for about 20-23 minutes, or until an inserted toothpick comes out clean.
Cool the bars in the pan. When ready to slice, lift the bars out of the pan using the overhang of the paper and place on a cutting board. Slice using a sharp knife. If you didn't line the pan, simply slice the bars in the pan.
Notes
Storage: Store in an airtight container for up to 4 days.
Nutrition: Details provided are an estimate only and based on 1 bar, assuming that all the cinnamon sugar topping was used and the pan sliced into 9 equal-sized bars.