One Bowl Snickerdoodle Bars

Preheat oven to 350°F. Line an 8 x 8" square baking pan with parchment paper and set aside.
In a large bowl, melt the butter and let it cool slightly.
1 cup unsalted butter
Add the sugars to the melted butter and stir well to combine.
1 ¼ cups sugar, ½ cup dark brown sugar,
Add the eggs one at a time and whisk well to combine. Room temperature eggs will be easier to incorporate into the batter. Add vanilla and stir.
2 large eggs,, 2 teaspoon vanilla
Add the flour, corn starch, cream of tartar, salt and ½ teaspoon of cinnamon and stir to combine. Batter will be thick. Spoon batter into prepared pan and smooth the top.
2¼ cups flour, 4 teaspoon corn starch, 1¼ teaspoon cream of tartar, 1 teaspoon salt, ½ teaspoon cinnamon
Combine 2 teaspoon cinnamon and 3 tablespoon sugar in a small bowl and sprinkle over the top of the batter. Bake in preheated oven for 30-35 minutes or until center is set and toothpick comes out with just a few crumbs on it.
2 teaspoon cinnamon, 3 tablespoon sugar
Cool completely and cut into squares.