Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper or silicone baking mats.

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

In a large mixing bowl, use an electric mixer to cream together the softened butter, vegetable oil, granulated sugar, and brown sugar until light and fluffy, about 2-3 minutes.

Add the egg, vanilla extract, and pumpkin puree to the wet mixture. Beat until well combined, scraping down the sides of the bowl as needed.

Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Do not overmix.

In a small bowl, combine the 1/4 cup granulated sugar and 2 teaspoons of cinnamon to create the coating mixture.

Scoop tablespoon-sized portions of dough and roll them into balls. Roll each ball in the cinnamon-sugar coating until fully covered.

Place the coated dough balls onto the prepared baking sheets, spacing them about 2 inches apart. Gently press down on each ball to slightly flatten them.

Bake in the preheated oven for 10-12 minutes, or until the edges are set and the tops look slightly crackled. Avoid overbaking to keep the cookies soft.

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