Preheat your oven to 350°F (175°C) and prepare a baking sheet lined with parchment paper.

In a medium mixing bowl, whisk together all-purpose flour, baking soda, cream of tartar, ground cinnamon, ground nutmeg, and salt.

In a large bowl, beat together softened unsalted butter, granulated sugar, and brown sugar until light and fluffy (about 2-3 minutes).

Mix in the large egg and vanilla extract until fully combined.

Gradually add the dry ingredients to the butter mixture, mixing on low until just combined, then gently fold in the chopped apple.

In a small bowl, combine granulated sugar and ground cinnamon for rolling mixture.

Scoop tablespoon-sized portions of dough, roll into balls, coat in cinnamon-sugar mixture, and place on the baking sheet.

Bake for 10-12 minutes or until edges are lightly golden and centers are slightly set.

Let the cookies cool on the baking sheet for about 5 minutes before transferring to a wire rack to cool completely.