Preheat oven to 170C. Grease a Cookie sheet with oil and line with parchment paper.
Sift together flour, cinnamon, all-spice and salt. Set aside.
In another bowl beat butter and sugar until smooth. Add in pumpkin puree and beat until combined.
Now add the dry ingredients and mix until just combined
Shape the dough into a log and cling wrap it and refrigerate for 15 minutes.
Remove the dough from fridge and cut in to thick circles and place it on the greased cookie sheet, leaving atleast an inch space between the cookies.
Bake in an preheated oven for 20-22 minutes or until the sides start to brown.
Let cool in pan for 5-10 minutes and then remove from pan and transfer to a wire rack. Let it cool completely, store it in an air-tight container.
The above measurements might yield approximately 18-20 shortbreads, depending upon the size and thickness one shapes them.