In a large bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy. Add the eggs and vanilla extract, mixing until well combined.

In another bowl, whisk together the flour, cream of tartar, baking soda, and salt. Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Roll the dough into small balls, about 1 inch in diameter. Roll each ball in the cinnamon-sugar mixture until well coated.

Place the coated balls on a parchment-lined baking sheet, spacing them about 2 inches apart.

Bake in the preheated oven for 10 minutes or until the edges are set but the centers are still soft. Allow the cookies to cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.