Preheat oven to 350 degrees F.
In a mixer, beat butter and both sugars.
Add oil, yolk, vanilla, and pumpkin.
Add flour, cream of tartar, salt, baking soda and cinnamon.
Lay parchment paper on cookie sheets and place large balls of dough on sheets.
Press down lightly on each.
Bake at 350 degrees F for 10 to 12 minutes.
Cool before frosting.