It looked like a fun project for our slow Sunday afternoon, so I sent him off to buy me some Marshmallow Fluff (not something I usually stock in my pantry) and started researching why Whoopie Pies are called such. I have only had a Whoopie pie once before in my life, it is a very regional treat that has roots in both Pennsylvania and Maine. Whoopie pies are actually 2 small cakes put together with a creamy filling and not a pie at all! People that grew up with Whoopie Pies are big fans and claim it's the best treat you can have! Whoopie pies can be made with chocolate cake with vanilla cream filling, like Oreos cookies, or with anything like pumpkin cake with cream cheese filling. There are many options, but I liked the traditional chocolate with marshmallow cream filling and decided to go with that.
½ Dutch processed cocoa powder
1 tsp baking soda
½ tsp salt
1 cup packed light brown sugar
8 tbsp (1 stick) unsalted butter, softened
1 large egg, room temperature
1 tsp vanilla extract
1 cup buttermilk
2 cups Marshmallow Fluff
¾ cup confectioner’s
10 tbsp (1 ¼ sticks) unsalted butter, softened
1 tsp vanilla extract
1/8 tsp salt
Preheat the oven to 350 degrees F. Adjust oven racks to the upper middle and lower middle positions. Line 2 baking sheets with parchment paper.
Whisk the flour, coca powder, baking soda, and salt together in a large bowl and set aside.
In a large bowl with an electric mixer, beat the sugar and butter together until light and fluffy, about 3-6 minutes. Beat in the egg until incorporated, scraping down the bowl and beaters as needed. Mix in vanilla.
Reduce Reduce the speed on the mixer to low and beat in 1/3 of the flour mixture. Beat in ½ of the buttermilk. Repeat with half of the remaining flour mixture, then the remaining buttermilk, and finally the remaining flour mixture. Give the batter a final stir using a rubber spatula to make sure it is thoroughly combined.
Using a ¼ cup measuring cup, scoop the batter into mounds and drop them, about 2 inches apart, on the prepared baking sheets (about 6 per sheet). Bake until the cakes bounce back when pressed, about 12-18 minutes, switching and rotating the pans halfway through baking. Let the cakes cool completely on the baking sheets, about 1 hour.
For the filling: Whip the fluff, confectioner’s sugar, butter, vanilla and salt together in a large bowl with an electric mixer on medium speed until light and fluffy, 4-8 minutes.
To assemble, sandwich about 3 tablespoons of the filling between the flattened sides of cooled cakes.