01 - Preheat oven to 375°F. Line two baking sheets with parchment paper.
02 - In a medium bowl, whisk together flour, cream of tartar, baking soda, and salt until evenly mixed.
03 - In a large bowl, use an electric mixer to beat softened butter and 1 1/2 cups granulated sugar until light and fluffy.
04 - Add eggs one at a time, mixing well after each addition. Stir in vanilla extract until fully blended.
05 - Gradually add dry ingredients to the wet mixture, mixing on low speed until just combined to avoid overmixing.
06 - In a small bowl, combine 1/4 cup granulated sugar with ground cinnamon and mix thoroughly.
07 - Roll dough into 1 1/2-inch balls. Roll each ball in the cinnamon-sugar mixture to coat evenly.
08 - Place coated dough balls spaced 2 inches apart on prepared baking sheets. Bake for 10 minutes or until edges are set and centers are soft.
09 - Allow cookies to cool on baking sheets for 5 minutes before transferring to wire racks to cool completely.