Ingredients:

  • 1 cup unsalted butter, softened
  • 1.5 cups granulated sugar
  • 2 large eggs, room temperature
  • 2 teaspoons vanilla extract
  • 2.75 cups all-purpose flour
  • 2 teaspoons cream of tartar
  • 1 teaspoon baking soda
  • 0.5 teaspoon kosher salt
  • 0.25 cup granulated sugar (for topping)
  • 1 tablespoon ground cinnamon (for topping)

Instructions:

  1. Preheat your oven to 350°F (175°C). Line a 9x13-inch baking pan with parchment paper, leaving an overhang on the sides, and lightly grease any exposed pan.
  2. In a large bowl, cream the softened butter and 1.5 cups of sugar together on medium-high speed for 2–3 minutes until the mixture is light and fluffy.
  3. Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract and scrape down the sides of the bowl.
  4. In a separate bowl, whisk together the flour, cream of tartar, baking soda, and salt. Gradually add the dry ingredients to the wet mixture on low speed, mixing just until no flour streaks remain.
  5. Press the thick dough into an even layer in the prepared 9x13 pan using a spatula or lightly floured hands.
  6. In a small bowl, mix the 0.25 cup sugar and 1 tablespoon cinnamon. Sprinkle the mixture evenly over the top of the dough.
  7. Bake for 25–30 minutes until the edges are light golden brown and the center is set but still soft.
  8. Allow the bars to cool completely in the pan on a wire rack before lifting them out and slicing into 24 squares.