1️⃣ Preheat the oven: Preheat your oven to 350°F (175°C). Grease or line a 9×13-inch baking pan with parchment paper.

2️⃣ Cream the butter and sugar: In a large mixing bowl, beat the softened butter and granulated sugar together until light and fluffy.

3️⃣ Add eggs and vanilla: Beat in the eggs one at a time, then add the vanilla extract and mix until well combined.

4️⃣ Mix dry ingredients: In a separate bowl, whisk together the flour, cream of tartar, baking soda, and salt.

5️⃣ Combine wet and dry: Gradually add the dry ingredients to the wet mixture, mixing just until the dough comes together.

6️⃣ Spread the dough: Press the dough evenly into the prepared baking pan.

7️⃣ Add cinnamon sugar topping: In a small bowl, mix the cinnamon and sugar. Sprinkle evenly over the top of the dough.

8️⃣ Bake: Bake in the preheated oven for 22–25 minutes or until the edges are lightly golden and a toothpick inserted in the center comes out clean.

9️⃣ Cool and cut: Let the bars cool in the pan for at least 20 minutes before slicing into squares.

🔟 Serve and enjoy: These bars are delightful warm or at room temperature—perfect with a glass of milk or a cup of coffee!