Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper.
In a large bowl, use an electric mixer to cream together the softened butter, granulated sugar, and brown sugar until light and fluffy.
Mix in the pumpkin puree, eggs, and vanilla extract until thoroughly combined.
In a separate bowl, whisk together the flour, baking soda, cream of tartar, salt, and pumpkin pie spice.
Gradually add the dry ingredients to the pumpkin mixture, mixing until just combined. Be careful not to overmix.
In a small bowl, combine the 1/4 cup granulated sugar with 1 teaspoon of pumpkin pie spice for rolling.
Use a cookie scoop or tablespoon to portion out dough, roll each ball in the cinnamon sugar mixture, and place them on the prepared baking sheets, spacing them about 2 inches apart.
Gently flatten each cookie ball with the bottom of a glass or your hand for a nice disc shape.
Bake the cookies in the preheated oven for 10-12 minutes, or until the edges are lightly golden.
Remove from the oven and let cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.