Ingredients

2 c. all-purpose flour

1/2 c. unsweetened cocoa powder (see Note)

1 tsp. baking soda

1/2 tsp. baking powder

1/2 tsp. salt

1 stick unsalted butter

1 c. light brown sugar

1 large egg

1 tsp. pure vanilla extract

1 c. buttermilk

2 stick unsalted butter

2 c. confectioners’ sugar

1 vanilla bean

1 jar marshmallow Fluff

Orange nonpareils or sanding sugar

Preparation

Step 1Make the cakes: Preheat the oven to 350 degrees F and line 2 large baking sheets with parchment paper. In a medium bowl, whisk the flour with the cocoa powder, baking soda, baking powder, and salt. In a large bowl, using a handheld electric mixer, beat the butter with the brown sugar at medium speed until fluffy, about 2 minutes. Beat in the egg and vanilla. At low speed, beat in the dry ingredients and buttermilk in 3 alternating additions; scrape down the side and bottom of the bowl as necessary.Step 2Using a 3-tablespoon ice cream scoop, scoop 12 level mounds onto each baking sheet, about 1 1/2 inches apart. Bake the cakes in the lower and upper thirds of the oven for about 16 minutes, until risen and firm; shift the pans from top to bottom and front to back halfway through baking. Transfer the sheets to racks and let the cakes cool completely.Step 3Meanwhile, make the filling: In a large bowl, beat the butter with the confectioners’ sugar and vanilla seeds until fluffy. Beat in the Marshmallow Fluff. Scrape the filling into a pastry bag fitted with a large plain tip.Step 4Pipe the filling onto the flat sides of 12 of the cakes and close the whoopee pies, pressing to evenly distribute the filling to the edges. Roll the edges in orange nonpareils and serve. Looking for more dessert ideas? Check out our homemade chocolate chip cookie recipes, apple pie recipes, and chocolate cake recipes.