1-First, preheat your oven to 350 degrees F and prepare a 9×13 inch pan by lightly greasing it. This sets the stage for even baking and easy removal. In a large bowl, cream together the butter, shortening, and 1 1/2 cups granulated sugar until smooth and fluffy.

2-Next, add the 2 large eggs and 2 teaspoons vanilla extract, mixing well to combine everything. Then, stir in the 2 3/4 cups all-purpose flour, 1 1/2 teaspoons cream of tartar, 1 teaspoon baking soda, and 1/4 teaspoon salt until just blended. Press the dough evenly into your prepared pan for a uniform base.

3-Mixing and Baking Details: Once the dough is in the pan, mix 1 1/2 tablespoons granulated sugar with 1 teaspoon ground cinnamon in a small bowl. Sprinkle this topping evenly over the dough for that extra crunch. Bake for 22-26 minutes, watching closely to avoid overbaking so the bars stay soft and chewy.

4-After baking, remove from the oven and let cool completely before cutting into squares. For dietary adaptations, substitute ingredients as mentioned earlier and adjust baking time if needed. This method ensures Snickerdoodle Bars with the perfect texture every time!