Classic Whoopie Pies Recipe

In a stand mixer, cream 0.5 cup softened butter and brown sugar on medium-high speed for 3 minutes until pale and fluffy. Beat in the egg and 1 tsp vanilla until the mixture is smooth.

Sift together the flour, cocoa powder, baking soda, and salt. With the mixer on low speed, alternate adding the dry ingredients and the buttermilk to the butter mixture in three batches, starting and ending with the dry ingredients. Mix just until combined.

Transfer the batter to a piping bag or use a cookie scoop to portion 2-inch rounds onto parchment-lined baking sheets, spacing them 3 inches apart.

Bake in a preheated oven until the cakes spring back when lightly touched (approximately 12 minutes). Transfer to a wire rack to cool completely.

Prepare the filling by beating 0.5 cup softened butter with powdered sugar, marshmallow fluff, 2 tsp vanilla, and heavy cream until light and stabilized.

Spread a generous dollop of filling on the flat side of one cake and top with another shell to create a sandwich.