01 -
Preheat oven to 350°F (175°C). Line a 9x13-inch baking pan with parchment paper for easy removal.
02 -
In a medium bowl, whisk together all-purpose flour, baking soda, cream of tartar, and salt until well mixed.
03 -
In a large mixing bowl, beat softened unsalted butter and 1 1/2 cups granulated sugar with an electric mixer for 2–3 minutes until pale and fluffy.
04 -
Add the egg and vanilla extract to the creamed mixture. Beat until fully incorporated and mixture is smooth.
05 -
Gradually add the dry ingredient mixture to the wet ingredients, mixing until a soft dough forms.
06 -
In a small bowl, blend 1/2 cup granulated sugar with 2 tablespoons ground cinnamon until thoroughly combined.
07 -
Evenly press dough into the prepared pan. Sprinkle cinnamon-sugar topping uniformly across the surface.
08 -
Bake in the preheated oven for 30–45 minutes or until edges are golden and center is set.
09 -
Allow bars to cool completely in the pan before lifting out and cutting into squares for serving.