Gather the ingredients - * Butter * Sugar * Flour * Cocoa powder * Baking soda * Buttermilk * Egg * Vanilla extract
– Add the softened butter and granulated sugar to the bowl of a stand mixer fitted with the paddle attachment. Beat on medium speed until light and fluffy. – In another bowl, whisk together the flour, cocoa powder, and baking soda. – In a third bowl, whisk together the buttermilk, egg, and vanilla.
With the mixer on low speed, alternate adding the dry ingredients and wet ingredients in batches. Make sure that it is mixed evenly.
Scoop the batter into small piles on the parchment lined baking sheet making sure to place them at least two inches apart.
Gather the frosting ingredients - * Butter * Powdered sugar * Vanilla extract * Powdered sugar
– Beat the butter, powdered sugar, and vanilla together. – Once all of the powdered sugar has been incorporated, turn the mixer to medium speed and beat until the frosting is light and fluffy. – Next, add the marshmallow fluff and fold it in gently.
Once the cakes have completely cooled, place them in similar sized pairs. Pipe the filling onto one of the flat sides of the cakes and top it with another cake.
Repeat with the remaining whoopie pies and enjoy. Store any leftovers in an airtight container in the fridge for up to two days.