Recipe courtesy of The America's Test Kitchen Family Baking Book
Makes 6 pies
Marshmallow creme with a thicker consistency (like Marshmallow Fluff) yields the best results in this recipe. If the filling is too soft to work with, chill it briefly; alternatively, if the filling seems stiff, 15 seconds in the microwave will do the trick.
- 2 cups all-purpose flour
- 1/2 cup Dutch-processed cocoa powder
- 1 teaspoon baking soda
- 1/2 teaspoon salt
- 8 tablespoons (1 stick) unsalted butter, softened
- 1 cup packed light brown sugar
- 1 large egg, room temperature
- 1 teaspoon vanilla extract
- 1 cup buttermilk
- 12 tablespoons (1 1/2 sticks) unsalted butter, softened
- 1 1/4 cups confectioners’ sugar
- 1 1/2 teaspoons vanilla extract
- 1/8 teaspoon salt
- 2 1/2 cups marshmallow creme (see note above)
- For the cakes: Adjust the oven racks to the upper-middle and lower-middle positions and heat the oven to 350 degrees. Line 2 large baking sheets with parchment paper. Whisk the flour, cocoa powder, baking soda, and salt together in a medium bowl.
- In a large bowl, beat the butter and brown sugar together with an electric mixer on medium speed until light and fluffy, 3 to 6 minutes. Beat in the egg and vanilla until combined, about 30 seconds, scraping down the bowl and beaters as necessary.
- Reduce the mixer speed to low and slowly beat in half of the flour mixture, followed by half of the buttermilk. Repeat with half of the remaining flour mixture and the remaining buttermilk. Add the remaining flour mixture until combined.
- Scoop six generous 1/4-cup mounds of batter onto each baking sheet, spaced about 2 inches apart. Bake the cakes until they spring back when pressed, 15 to 18 minutes, switching and rotating the baking sheets halfway through baking. Let the cakes cool completely on the baking sheets, about 1 hour.
- For the filling: Beat the butter and confectioners’ sugar together in a medium bowl with an electric mixer on medium speed until light and fluffy, about 2 minutes. Beat in the vanilla and salt. Beat in the marshmallow creme until incorporated, about 2 minutes.
- To serve, spread 1/3 cup of the filling evenly over the bottom of a cake, then make a sandwich by pressing the bottom of another cake onto the filling; repeat with the remaining cakes and filling.