Chocolate Whoopie Pies with Vanilla Buttercream
Ingredients
For the cookies:
12 Tbs. (1 1/2 sticks) (6 oz./185 g) unsalted butter, at room temperature
3/4 cup (6 oz./185 g) granulated sugar
2 eggs, at room temperature
1 tsp. vanilla extract
1/2 cup (2 1/2 oz./75 g) all-purpose flour
1/2 cup (1 1/2 oz./45 g) unsweetened natural cocoa powder
1/4 tsp. baking powder
1/4 tsp. baking soda
1/8 tsp. kosher salt
For the buttercream filling:
3 cups (12 oz./375 g) confectioners’ sugar
8 Tbs. (1 stick) (4 oz./125 g) unsalted butter, at room temperature
2 Tbs. milk, plus more, if needed
1 tsp. vanilla extract
1/4 tsp. salt
Directions
Preheat an oven to 350°F (180°C). Lightly grease the star whoopie pie pan with butter or nonstick cooking spray.
To make the cookies, in the bowl of an electric mixer fitted with the flat beater, beat the butter on high speed until fluffy and pale yellow. Add the sugar and beat until lightened. Add the eggs and vanilla and beat until well blended.
Sift the flour, cocoa, baking powder, baking soda and salt into a bowl. Add to the butter mixture and beat on low speed just until blended.
Spoon the batter into the prepared pan, using one generous tablespoonful (25 g) of batter per well. Use a spatula or the back of a spoon to spread the batter evenly in the well. Bake until a toothpick inserted into the center of the cookies comes out clean, 10 to 12 minutes. Transfer the cookies to wire racks and let cool completely. If the tops of the cookies domed while baking, use a knife to carefully slice off the dome and create a flat surface.
Meanwhile, make the buttercream filling: In the bowl of an electric mixer fitted with the flat beater, combine the confectioners’ sugar, butter, the 2 Tbs. milk, the vanilla and salt and beat on low speed until combined, about 1 minute. Stop the mixer and scrape down the sides of the bowl. Increase the speed to medium and beat until fluffy, about 3 minutes. If the frosting is dry, add more milk, 1 tsp. at a time, until it is creamy but still holds peaks.
To assemble the whoopie pies, spread the flat side of half of the cookies with one 1 Tbs. of the buttercream filling. Top with a second cookie, flat side down, pressing lightly to make a cookie sandwich. Makes about 10 sandwiches.
Williams-Sonoma Test Kitchen