Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a medium bowl, whisk together flour, baking soda, cream of tartar, cinnamon, and salt.
In a separate large bowl, beat together the butter, granulated sugar, and brown sugar until light and fluffy.
Add the egg and vanilla extract to your butter-sugar mixture, beating until well combined.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Gently fold in the chopped apple until evenly distributed throughout the dough. Then roll tablespoon-sized portions of dough into balls before rolling each ball in a cinnamon-sugar mixture.