Recipe notes: We preferred the smaller pies described here, but if you want a really decadent treat, you can use 1/4-cup scoops of dough to create the cakes. The yield will be 8 large sandwiches.
The cakes and filling can be made 1 day in advance and stored at room temperature in airtight containers. The cakes can be somewhat sticky, so store them in a single layer without touching. The assembled whoopie pies can be stored individually wrapped at room temperature for 1 day.
Marshmallow Fluff is a New England ingredient available in certain other parts of the country. Marshmallow creme, more widely available, is a thinner consistency than Fluff. If you make your filling with marshmallow creme, you may need to add a bit more sugar to stiffen it up sufficiently.
- FOR THE CAKES
- 8 tablespoons (1 stick/113 grams) unsalted butter, at room temperature (at least 65 degrees)
- 1 cup (213 grams) light or dark brown sugar, packed
- 1 teaspoon espresso powder (optional)
- 1 teaspoon baking powder
- 1/2 teaspoon baking soda
- 3/4 teaspoon kosher salt
- 1 teaspoon vanilla extract
- 1 large egg, at room temperature
- 1/2 cup (43 grams) Dutch-process cocoa powder
- 2 cups (283 grams) all-purpose flour
- 1 cup (240 milliliters) milk, at room temperature
- FOR THE FILLING
- 1 cup (177 grams) vegetable shortening
- 1 cup (113 grams) confectioners' sugar
- 1 1/3 cups (167 grams) Marshmallow Fluff or marshmallow creme
- 1/4 teaspoon kosher salt dissolved in 1 tablespoon water
- 1 1/2 teaspoons vanilla extract
Preheat the oven to 350 degrees with the rack in the middle. Lightly grease (or line with parchment) two large, rimmed baking sheets.
Make the cakes: In the bowl of a stand mixer fitted with a paddle attachment, or using a hand mixer and a large bowl, beat together the butter, brown sugar, espresso powder (if using), baking powder, baking soda, salt and vanilla on medium-high until smooth. Scrape down the sides of the bowl. Add the egg and beat again until smooth.
Add the cocoa and mix on low to combine.
Gradually add the flour to the batter, alternating it with the milk, beating on low until smooth. Scrape down the sides and bottom of the bowl, and beat again on low briefly to soften and combine any chunky scrapings.
Drop the dough in 2-tablespoon portions onto the prepared baking sheets (16 per sheet), leaving plenty of room between the cakes; they’ll spread. (A No. 30 disher works well here.)
Bake the cakes for 11 to 12 minutes, until they’re set and firm to the touch. Remove from the oven and cool on the pans. While still lukewarm, use a spatula to separate them from the pan or parchment; then let cool completely.
Make the filling: In the bowl of a stand mixer fitted with a paddle attachment, or in a large bowl using a hand mixer, beat together the shortening, confectioners’ sugar and Marshmallow Fluff until well combined. Start on low to avoid a cloud of sugar, then increase to medium.
Add the prepared salt water to the marshmallow mixture, beating on low. Add the vanilla and beat until smooth.
Spread the flat side of half the cakes with the filling. Top with the remaining cakes, flat side toward the filling. Keep wrapped individually in plastic wrap until ready to serve.
Adapted from a King Arthur Flour recipe.
Tested by Becky Krystal; email questions to email@example.com.
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Calories: 340; Total Fat: 18 g; Saturated Fat: 7 g; Cholesterol: 30 mg; Sodium: 125 mg; Carbohydrates: 43 g; Dietary Fiber: 1 g; Sugars: 25 g; Protein: 3 g.