Prepare the Dough:
In a medium-sized mixing bowl, use an electric mixer to cream together the granulated sugar, brown sugar, butter, shortening, and vanilla extract for 2 minutes, or until light and fluffy.
Add the eggs one at a time, beating well after each addition. Scrape the sides of the bowl as needed.
Combine Dry Ingredients:
In a separate bowl, sift together the flour, pumpkin spice instant pudding mix, cream of tartar, baking soda, and salt.
Mix Wet and Dry Ingredients:
Lower the mixer speed and gradually add the dry ingredients to the creamed mixture. Mix just until fully combined. Cover the dough and chill for at least 1 hour or overnight for best results.
Bake the Cookies:
Preheat the oven to 375°F (190°C). Line two baking sheets with parchment paper and set aside.
In a shallow dish, mix together the ½ cup of granulated sugar and 2 tsp of ground cinnamon for rolling.
Shape and Bake:
Use a 2 oz ice cream scoop or tablespoon to divide the dough. Shape each portion into a ball and roll in the cinnamon-sugar mixture.
Place the dough balls on the prepared baking sheets at least 2 inches apart. Flatten the centers slightly using the bottom of a glass.
Bake and Cool:
Bake for 10-12 minutes, or until the edges are set and the centers are soft. Cool the cookies on the baking sheet for 5 minutes, then transfer to a cooling rack.
Storage:
Store the Pumpkin Spice Snickerdoodles in an airtight container at room temperature to keep them soft and fresh.