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

In a mixing bowl, whisk together the flour, baking soda, cream of tartar, salt, cinnamon, and nutmeg.

In another bowl, cream together the softened butter, brown sugar, and granulated sugar until light and fluffy.

Mix in the pumpkin puree, egg, and vanilla extract until well combined.

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

In a small bowl, mix together the granulated sugar and cinnamon for the coating.

Using a cookie scoop, portion out the dough and roll each ball in the cinnamon-sugar mixture.

Place the coated dough balls on the prepared baking sheet and bake for 10-12 minutes, until the edges are set.

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