Chocolate Whoopie Pies

Transfer to a wire rack to cool.
In a mixer or using a hand mixer, beat shortening and marshmallow fluff together.
Slowly add in powdered sugar and vanilla extract.
Once whoopee pies are completely cool, spoon filling (1-2 tablespoons) onto flat side of cake and top with second cake to create a little sandwich. Optional: sprinkle top with powdered sugar.
Serve immediately or wrap individually in plastic wrap to preserve freshness.