In a small bowl stir together the ¼ cup of the sugar, 1 teaspoon of the pumpkin pie spice, and the cinnamon. Set aside.
In large bowl of electric mixer combine the butter, shortening, remaining 1 cup granulated sugar, and brown sugar. Beat until light and fluffy. Mix in the pumpkin and vanilla.
In a medium bowl whisk together the flour, cream of tartar, baking soda, baking powder, the remaining 1 teaspoon pumpkin pie spice, and salt. Gradually add to the pumpkin mixture, stirring until well combined. Cover and refrigerate the dough at least 3 hours, or overnight. Dough will also keep for several days.
When ready to bake, preheat oven to 375 degrees F. Use a nonstick pan or line baking sheet with parchment. Roll dough into 1-inch balls or use a cookie scoop. Toss each ball in the reserved cinnamon-sugar mixture. Place coated cookie balls 2-inches apart on baking sheet. Bake until edges are just brown, about 8 to 9 minutes. Cool cookies on baking sheet for 2 minutes before removing to a cool rack and cool completely.
Recipe by The Culinary Cellar at https://theculinarycellar.com/pumpkin-snickerdoodles/