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, nutmeg, and salt.

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

Beat in the egg and vanilla extract until well combined.

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

Fold in the finely chopped apples gently using a spatula.

In a small bowl, combine sugar and cinnamon for rolling. Roll the dough into 1-inch balls and coat with the mixture.

Place the rolled dough balls on the prepared baking sheet, spaced 2 inches apart, and bake for 10-12 minutes until golden.

Cool for 5 minutes on the baking sheet before transferring to a wire rack.