Pumpkin Spice Whoopie Pies with Biscoff Filling

Ingredients:
1 box spice cake mix
15 oz can pureed pumpkin
1 egg
1/2 cup water

Biscoff Frosting:
1/2 cup room temperature butter
1 cup biscoff
1 1/2 cup powdered sugar

Directions:
1.)  Preheat oven to 350 degrees and line two baking trays with parchment paper. 
2.)  In a medium bowl, combine cake mix, pumpkin, eggs and water and mix until very few lumps are visible.
3.)  Using a small cookie scoop, scoop out rounded scoops of batter onto baking trays.  (These do not spread so you may want to flatten and smooth the tops of each mound with the back of the scoop as you scoop them out.  I was able to do 12 per tray)
4.)  Bake in the oven for approximately 10-12 minutes.
5.)  While baking, begin to make frosting by creaming butter and biscoff.  Slowly add in powdered sugar and beat until light and fluffy. 
6.)  Spoon frosting into a quart-sized ziplock baggie and cut tip off of one corner.
7.)  After whoopie pies have COMPLETELY cooled, pipe frosting onto half of whoopee pies starting with the outer rim of each one.
8.)  Place other half of whoopie pie on top of each accordingly and serve : )