MINI WHOOPIE PIES

Steps:

• Arrange the oven racks in the upper and lower thirds of the oven and preheat the oven to 425°F. Line 2 large baking sheets with parchment paper.
• Make the cakes:
• Whisk together the flours, cocoa, baking soda and salt in a medium bowl.
• Cream the butter and sugar in the bowl of an electric mixer at high speed until fluffy, about 4 minutes. Add the egg and milk and beat at medium speed until incorporated. At low speed, add the flour mixture in 2 batches, alternating with the milk, mixing until just blended.
• Using a half-tablespoon measure, drop 18 generous teaspoons of batter onto each sheet, leaving about 2 inches between cakes. Bake the 2 sheets at the same time, 5 to 7 minutes, until springy to touch. Let cool on the sheets for 5 minutes, and transfer to racks to cool completely. Change the parchment and repeat using the remaining batter (72 cakes in total).
• Make filling:
• Beat the butter and confectioners' sugar at low speed until blended and then beat at high speed until fluffy, about 5 minutes. Add the vanilla and marshmallow cream and mix at low speed until blended, about 1 minute.
• Match pairs of cake with the same shapes and spread the bottom side of 1 cake with filling and sandwich together with the other cake. (Store the finished whoopee pies in a covered plastic container and chill for up to 3 days.)