Mini Whoopie Pies

Work: 45 minutes
Total: 1 hour 15 minutes

Ingredients
3/4 cup unsweetened cocoa powder
1 2/3 cups all-purpose flour
1 1/2 teaspoons baking soda
1/2 teaspoons salt
1/4 cup unsalted butter, softened
1/4 cup vegetable shortening
1/2 cup granulated sugar
1/2 cup packed light-brown sugar
1 egg
1 cup milk
1 teaspoons vanilla extract
Meringue Buttercream (recipe below)
1/3 cup each orange and yellow sprinkles

1. Heat oven to 375 degrees Fahrenheit. Line three baking sheets with parchment. Dip a 1-1/4-inch round cookie cutter in extra cocoa and tap onto parchment to create a cookie outline; re-dip in cocoa as needed and make additional outlines 1 inch apart on both baking sheets; set aside. Whisk together cocoa, flour, baking soda, and salt; set aside.
2. In a mixing bowl, beat together the butter, shortening, and sugars until smooth, about 2 minutes. Add egg and vanilla and beat until fluffy, 2 minutes. Stir in half the flour mixture, then the milk, and beat to combine. Add the remaining flour mixture and beat together, scraping down sides of bowl.
3. Transfer batter to a piping bag fitted with a coupler, or a 1/2-inch plain tip. Pipe onto parchment, filling the cocoa outlines with mounds. Bake, one sheet at a time, until cookies spring back to the touch, 10 to 12 minutes. Cool on baking sheets 10 minutes. Then, with a metal spatula, transfer to a wire rack to cool completely.
4. Spread about 1 tablespoon buttercream on flat sides of half the cookies and sandwich together with remaining cookies. Cover edges with colored sprinkles. Can be made up to 1 day ahead and stored chilled. Bring to room temperature before serving. Makes about 48.

Meringue Buttercream

Work: 15 minutes
Total: 30 minutes

Ingredients
5 large egg whites
1 1/4 cups sugar
2 cups unsalted butter, cut into pieces, softened
1 teaspoon vanilla extract

1. Whisk together egg whites and sugar in a heatproof mixing bowl over a pan of simmering water until sugar has dissolved, about 5 minutes. Test by rubbing the mixture between your fingers -- you shouldn't feel any sugar crystals.
2. Transfer bowl to the mixer stand with whisk attachment or use a handheld mixer and beat on high until it cools and stiff peaks form, 10 to 12 minutes.
3. Reduce speed to medium-high and add butter a little at a time. (Buttercream may curdle but will become smooth as you continue to beat it.) Add vanilla.
4. Use within a few hours or refrigerate up to a week. Before using, bring to room temperature and beat on low until smooth. Makes about 5 cups.