Mochaccino Cupcakes

Mocha Cupcake:
* 3/4 cup butter
* 3 eggs
* 1-3/4 cups all-purpose flour
* 1 cup unsweetened cocoa powder
* 1 teaspoon baking soda
* 3/4 teaspoon baking powder
* 1/2 teaspoon salt
* 1 cup milk
* 1/2 cup strong brewed coffee, cooled
* 2 cups sugar
* 2 teaspoons vanilla
* 1 cup dark, bittersweet, or semisweet chocolate pieces

Coffee Swiss Meringue Buttercream:
Put ¾ cup sugar, 3 egg whites and pinch salt into the top of a double boiler over a pan of simmering water. Whisking constantly, cook until sugar has dissolved and mixture is warm (about 160 degrees). Pour heated egg whites into the bowl of an electric mixer fitted with the whisk attachment. Beat egg white mixture on high speed until it forms stiff (but not dry) peaks. Continue beating until fluffy and cooled, about 7 minutes total. Switch to the paddle attachment. With mixer on medium-low, add 1 ½ stick butter two tablespoons at a time, beating well after each addition. Increase speed to medium-high; continue beating until frosting appears thick, about 3 minutes. Meanwhile, stir 1 1/2 tsp instant coffee into 1 tbsp hot water until dissolved, then put it in the refrigerator or freezer until it comes down to room temperature. Reduce mixer speed to low and add coffee mixture. Add 1 T coffee liqueur and ½ cup powdered sugar. Continue beating 1 minute to reduce air bubbles.