Beat softened butter, granulated sugar, and brown sugar until light and fluffy.
Mix in pumpkin puree, egg, and vanilla extract until combined.
In a separate bowl, whisk flour, baking powder, cream of tartar, baking soda, and salt.
Gradually add dry mix to wet mix. Mix to form a soft dough.
Cover and refrigerate dough for 1 hour.
Preheat oven to 350°F (175°C). Line baking sheet.
Roll chilled dough into balls. Coat with cinnamon-sugar mixture.
Place coated dough balls on baking sheet. Bake 10-12 minutes until edges are golden.
Cool on sheet for a bit, then transfer to a wire rack.
Once cooled, savor the fall flavors of these Pumpkin Snickerdoodle Cookies.