Preheat your oven to 350°F (175°C).
In a medium bowl, whisk together flour, cream of tartar, baking soda, and salt. Set aside.
In a stand mixer, cream together the softened butter and sugar until light and fluffy.
Add eggs and vanilla extract; mix until well combined.
Gradually add the dry ingredients to the wet mixture, mixing until fully incorporated.
In a small bowl, mix together sugar and cinnamon for coating.
Scoop dough into 1-inch balls and roll them in the cinnamon-sugar mixture.
Place dough balls on an ungreased baking sheet, spaced about 2 inches apart.
Bake for 8-10 minutes or until edges are set but centers remain soft.
Let cookies cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.