Preparation Steps

• Preheat oven to 375°F (190°C). Line baking sheets with parchment paper.
• In a large bowl, cream together softened butter, granulated sugar, and brown sugar until light and fluffy.
  0.25 cup unsalted butter
• Beat in the egg and vanilla extract until well combined.
  0.25 cup unsalted butter
• In a separate medium bowl, whisk together flour, cream of tartar, baking soda, and salt.
  0.25 cup unsalted butter
• Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.
• In a small bowl, combine the sugar and cinnamon for the coating.
  0.25 cup unsalted butter
• Roll dough into 1-inch balls and then roll each ball in the cinnamon-sugar mixture.
• Place dough balls onto the prepared baking sheets, about 2 inches apart.
• Bake for 9-12 minutes, or until the edges are lightly golden and the centers are still slightly soft.
• Let cookies cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.