Preheat your oven to 350°F (175°C) and line baking sheets with parchment paper. In a medium bowl, whisk together the flour, cream of tartar, baking soda, and salt; then set aside.

In a large bowl, cream together the softened butter and 1 1/2 cups granulated sugar until the mixture is light and fluffy. Beat in the eggs one at a time, followed by the vanilla extract, ensuring everything is well combined.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined and a soft dough forms. In a small separate bowl, combine 1/4 cup granulated sugar and the ground cinnamon for the coating.

Roll rounded tablespoons of dough into balls, then generously roll each ball in the cinnamon-sugar mixture until fully coated. Place the coated dough balls about 2 inches apart on the prepared baking sheets.

Bake for 8-10 minutes, or until the edges are set but the centers still appear soft. Do not overbake to ensure the cookies remain chewy. Let the cookies cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely.