FOR THE COOKIES: Preheat oven to 350 degrees. In a mixing bowl whisk together flour, slightly ground oats, cornstarch, baking powder, baking soda, salt, cinnamon, nutmeg, ginger and cloves for 30 seconds, set aside.
In the bowl of an electric stand mixer fitted with the paddle attachment, whip together 1 cup butter and brown sugar until pale and fluffy, occasionally scraping down sides and bottom of bowl.
Mix in egg and vanilla (you could also add in a few drops of red or orange food color for a more vibrant color of cookie).
Blend in half of the pumpkin puree, then with mixer set on low speed slowly add in half of the dry mixture and blend just until combined, then repeat with remaining pumpkin and dry mixture.
Allow batter to rest 10 minutes, then drop dough 2 Tbsp at a time onto Silpat or parchment paper lined baking sheets, spacing cookies 2- inches apart.
Bake in preheated oven 10 - 12 minutes. Remove from oven and allow to cool on baking sheet several minutes before transferring to a wire rack to cool completely.
Once cool spread cream filling onto bottom side of half of the cookies and sandwich with remaining cookies. Store in an airtight container at room temperature.
FOR THE FILLING: In the bowl of an electric stand mixer fit with paddle attachment, whip butter and shortening on medium-high speed, until pale and fluffy, about 3 - 4 minutes.
Add powdered sugar and blend on low speed until combine, then increase speed to medium-high and whip for 1 minute. Mix in marshmallow creme.
Notes
*Pulse quick oats in a food processor about 15 times, you still want some texture.