Preheat the oven to 350 degrees. Prep cookie sheets with a sheet of parchment or spray with non stick spray, set aside.
In the bowl of a stand mixer, combine the butter and sugars, cream until light and fluffy. Scrape down the sides and mix again.
Add in the egg, pumpkin puree, oil, milk, cream of tartar, vanilla, salt, baking soda, and pumpkin pie spice.
Mix thoroughly. Add in the flour and combine well. Scrape down the sides and mix again. Fold in the chocolate chips by hand until combined.
Scoop out spoonfuls of dough and place on the prepared cookie sheets. Leave about 2 inches of space around each cookie.
Bake in preheated oven for approximately 10-12 minutes or until edges are set and slightly browned.
Allow to cool for 10 minutes before serving.