Preheat the oven to 350°F and line two baking sheets with parchment paper and set aside.
In a medium bowl, sift together the flour, cinnamon, baking powder, baking soda, and salt. Set aside.
With an electric mixer, beat oil and sugar together. Addthe pumpkin and egg and mix well. Gradually add flour mixture, mixing until just combined.
With a piping bag, pipe 2-inch diameter circles onto baking sheet approximately 2 inches apart.
Bake 8 to 10 minutes, until slightly browned on edges and spring back when touched. Cool 5 minutes before moving to cooling rack. Cool completely before icing.
Filling
Beat all ingredients together until smooth and creamy.
Pipe on spread filling onto one cookie. Top with a second. Do this with remaining cookies.
Notes
These are mini whoopie pies. You could make them larger by piping bigger amounts onto the pan but you will need to increase the bake time. The cakes are done when they spring back after being touched.
Vegetable or canola oil can be used in place of olive oil for a milder flavor.