Ingredients
- FOR WHOOPIE PIES:
- ◾1/2 cup unsalted butter, at room temperature
- ◾1 cup brown sugar
- ◾1 teaspoon instant espresso powder (optional)
- ◾1 teaspoon baking powder
- ◾1/2 teaspoon baking soda
- ◾3/4 teaspoon salt
- ◾1 teaspoon vanilla
- ◾1 egg
- ◾1/2 cup cocoa, sifted
- ◾2 1/3 cups all-purpose flour
- ◾1 cup milk
- FOR BUTTERCREAM FILLING:
- ◾10 tablespoons unsalted butter, at room temperature
- ◾1 1/4 cups powdered sugar
- ◾Pinch of salt
- ◾2 teaspoons vanilla
- ◾1 tablespoon heavy cream
Preparation
Step 1
MAKE WHOOPIE PIES:
Preheat oven to 350˚F and set aside two baking sheets lined with parchment paper.
In a large bowl, beat together butter, brown sugar, espresso powder (if using), baking powder, baking soda, salt, and vanilla. Add egg and beat until smooth. Add cocoa and stir to combine. Add all-purpose flour and milk alternately, and stir until thoroughly combined.
Transfer batter to a piping bag and pipe 1-tablespoon sized mounds onto the baking sheets, being sure to keep at least 2 inches of space between each mound. With a damp finger, lightly pat the tops of the cakes to flatten and even them out. Bake for 8 to 10 minutes, until the cakes are set and firm to the touch. Remove from the oven and cool for a few minutes, then transfer to cooling racks to cool completely.
MAKE FILLING:
In a large bowl, whip butter over medium-high speed until smooth, about 30 seconds. Add powdered sugar and salt and beat on medium-high speed until smooth, about 1 to 2 minutes. Mix in vanilla and heavy cream on low speed until just incorporated, then increase speed to medium-high and whip for 4 minutes, making sure to stop a few times to scrape down the sides of the bowl.
Transfer filling to a piping bag.
To assemble the cookies, match them up in pairs by size. Pipe filling onto the flat side of one cookie, and then place the second cookie on top to create a sandwich.
Leftovers may be refrigerated.