Preheat your oven to 400°F (200°C) and line baking sheets with parchment paper.

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

In a large bowl, cream together the softened butter and granulated sugar until light and fluffy.

Beat in the eggs one at a time, then stir in the vanilla extract.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

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

Roll the dough into 1-inch balls, then roll each ball in the cinnamon sugar mixture.

Place the coated dough balls 2 inches apart on the prepared baking sheets and bake for 8-10 minutes, or until the edges are set but the centers are still soft.

Let the cookies cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely.