Mocha Cupcakes with Silky Chocolate Italian Meringue Buttercream

For the Mocha Cupcakes:

• 1 1/2 sticks unsalted butter (12 tablespoons), softened to room temperature
• 1 3/4 cups granulated sugar
• 1/2 teaspoon salt
• 1 1/2 teaspoons baking soda
• 2 teaspoons pure vanilla extract
• 2 cups all-purpose flour (8 1/2 ounces by weight)
• 3/4 cup natural cocoa powder (not Dutch-processed)
• 4 large eggs, at room temperature
• 1 1/2 cups very strong brewed coffee, cooled to room temperature

For the Chocolate Italian Meringue Buttercream:

• 3 large egg whites (discard shells; save yolks for another use)
• 1/4 cup light corn syrup
• 1 cup granulated sugar
• 1/3 cup water
• 1/2 teaspoon cream of tartar
• 1/2 teaspoon salt
• 1 cup butter, softened to room temperature
• 1/2 cup vegetable shortening
• 2 ounces unsweetened chocolate, melted and slightly cooled
• 2 teaspoons pure vanilla extract

For garnish:

• Dark chocolate for grating over the finished cupcakes

To make the mocha cupcakes:

• Preheat the oven to 350°F. Line two 12-cupcake pans with liners and set aside.
• In a mixer fitted with the paddle attachment (or with a hand mixer), beat the butter, sugar, salt, baking soda, and vanilla for about 5 minutes, until fluffy and lighter in color. Add the eggs one at a time, beating well after each addition.
• Sift the flour and cocoa powder together to remove lumps. Add about one-third of the flour mixture and fold gently into the batter, scraping the bowl as needed. Add half of the cooled coffee and mix gently. Repeat with another third of the flour, the remaining coffee, and finally the last third of flour, mixing until just combined.
• Divide batter among the prepared liners, filling each about two-thirds full. Tap pans gently to release air bubbles. Bake 23–25 minutes, or until a toothpick inserted into the center comes out clean. Allow cupcakes to rest in the pans for 5 minutes, then transfer to a rack to cool completely before frosting.

To make the chocolate Italian meringue buttercream:

• Whip together the butter and shortening until smooth and fluffy. Transfer to a clean bowl and thoroughly clean the mixer and attachments.
• Place the egg whites in the clean mixer bowl fitted with the whisk attachment.
• Combine corn syrup, sugar, and water in a medium saucepan over medium-high heat. Stir until sugar dissolves, cover, bring to a boil, and boil for 3 minutes without stirring. Remove the lid, attach a candy thermometer, and cook to the soft-ball stage (about 240°F).
• Begin whipping the egg whites on low until foamy. Add cream of tartar and salt, then increase to high and whip to soft peaks.
• When the syrup reaches 240°F, remove from heat. Carefully pour about one-quarter of the hot syrup down the side of the mixing bowl while the mixer runs on low, then gradually increase speed. Turn the mixer off briefly and add half of the remaining syrup, then turn on and beat. Add the rest of the syrup and beat on high until the meringue is completely cooled to room temperature—this can take about 20 minutes. Caution: hot syrup can burn; take care when pouring.
• With the mixer on low, add the butter in pieces, beating well after each addition. If the mixture looks separated, stop adding butter and beat until it comes back together. Once all butter is incorporated, add melted chocolate and vanilla and whip until evenly colored and smooth. Chill briefly if the buttercream is too soft to pipe.
• Pipe or spread the buttercream onto cooled cupcakes and grate dark chocolate over the tops to finish.

*Do not add the hot syrup while the mixer is running without extreme caution. Hot syrup can splash and cause severe burns. Pour slowly and protect your skin.