For the cupcakes
1 cups boiling water
1/2 cup unsweetened cocoa powder
1 1/2 cups all-purpose flour
1 teaspoons baking soda
1/2 teaspoon baking powder
1/2 teaspoon salt
1/2 cup butter, softened
1 cup granulated sugar
2 teaspoon vanilla extract
2 tablespoons espresso powder
for the frosting
1 cup (2 sticks) unsalted butter, at room temperature
2 1/2 cups powdered sugar
1 teaspoons vanilla extract
1 teaspoon coffee or espresso extract
2 teaspoons espresso powder
Preheat oven to 350F.
Combine vanilla and espresso powder until dissolved; set aside.
In medium bowl, pour boiling water over cocoa, and whisk until smooth. Let mixture cool. Sift together flour, baking soda, baking powder and salt; set aside. In the bowl of a stand mixer, cream butter and sugar together until light and fluffy. Beat in eggs one at time, then stir in vanilla and espresso powder. Add the flour mixture alternately with the cocoa mixture, ending with the flour.
Fill the lined muffin cups three-quarters full, being careful not to overfill. Bake until a toothpick inserted in the center of the cupcake comes out clean, about 18 to 20 minutes. Cool the cupcakes in the pan for 5 minutes, then transfer to a wire rack to cool completely.
To make the frosting. Combine the espresso powder into the vanilla and coffee extract until dissolved; set aside.
Using the whisk attachment of a stand mixer, whip the butter on medium-high speed for 5 minutes, stopping to scrape the sides of the bowl. Reduce the mixer speed to low and add the powdered sugar a little at a time, waiting until it is mostly incorporated before adding more. Once all of the powdered sugar has been added, scrape the sides of the bowl and increase the speed to medium-high and whip until fluffy, about a minute or two. Add the espresso and vanilla mixture and continue to mix at medium-high until it is completely incorporated, scraping the sides as necessary.
Pipe frosting onto the cupcakes and garnish with chocolate shavings.