In a medium bowl, mix flour, cream of tartar, baking soda, salt, and spices until combined. Set aside.
In the bowl of stand mixer, fitted with a paddle attachment, cream the sugar and eggs until light a fluffy, about 2 minutes.
Add the egg and beat at medium-low speed until combined. Add pumpkin puree and continue on medium-low until combined.
Add the dry ingredients to the wet ingredients about 1/2 cup at a time, mixing on medium-low until incorporated before adding the next 1/2 cup. When all dry ingredients are incorporated. Remove paddle attachment and scrape the sides of the bowl with a spatula. Give the batter a couple mixes until all the scrapes are incorporated.
Using a cookie scoop (mine is the size of a tablespoon), take a heaping scoop of dough and place on a greased cookie sheet. Repeat for all of the dough until gone. We are going to place these in the fridge so they can be touching. Refrigerate for 8 hours, or overnight so that the dough can get fully-chilled.