1. Preheat the oven to 375°F (190°C) and line baking sheets with parchment paper or silicone baking mats.

2. In a medium bowl, whisk together the flour, cream of tartar, baking soda, and salt.

3. In a large mixing bowl, beat the softened butter and sugar together until light and fluffy.

4. Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.

5. Gradually add the dry ingredients to the wet ingredients and mix until a soft dough forms.

6. In a small bowl, combine the cinnamon and sugar for the coating.

7. Scoop the dough into evenly sized balls and roll each one in the cinnamon-sugar mixture.

8. Place the coated dough balls on the prepared baking sheets, leaving space between each cookie.

9. Bake for 9 to 11 minutes until the edges are lightly golden and the centers remain soft.

10. Allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack.

11. Serve warm or store in an airtight container once fully cooled.