Preheat oven to 350 degrees F. Cover baking sheets with parchment paper
In a mixer, cream powdered sugar, granulated sugar and butter.
Add in oil and mix until combined.
Add in egg yolk, vanilla and pumpkin puree, mix until combined
Whisk together flour, cream of tartar, salt, baking soda, cinnamon, nutmeg, ginger and cloves.
Add this dry mixture to wet mixture.
Dough will be stick. If it is too sticky to work with refrigerate for 20-30 minutes.
Roll dough (2 Tbsp) into a ball and place on covered cookie sheet, 2 inches apart.
Dip the bottom of a glass into the 1/2 cup sugar (grease or moisten the bottom of the glass to get sugar to stick) and press into each cookie, to about 1/4 inch thick. Dip glass into sugar between each cookie.
Bake cookies for about 10 minutes.
Buttercream
Combine sugar, cinnamon and butter.
Add in milk until a nice spreading consistency is found.