chocolate guinness cupcakes

1. Preheat the oven to 350°F. Line a 12-cup muffin pan with paper liners and set aside. Whisk together flour and baking soda in a medium bowl. Set aside.
2. Combine Guinness, butter, salt and espresso powder in a medium saucepan set over medium-low heat. Cook gently until butter has melted. Whisk in cocoa powder, granulated sugar and brown sugar; let cool slightly.
3. Meanwhile, combine sour cream, egg and vanilla in a large bowl and whisk until smooth. Add Guinness mixture and whisk until combined. Whisk in dry ingredients until just combined. Fill each liner 2/3 full of batter. Bake for 22- 24 minutes, or until a toothpick inserted in the center comes out clean. Cupcakes will sink in the center-- it's okay. Let cupcakes cool 5 minutes in the pan, then transfer to a wire rack to cool completely.
4. While cupcakes bake, prepare the ganache filling. Place bittersweet chocolate in a heatproof bowl. Heat cream in a small saucepan over medium heat until bubbles just begin to form at the edges. Pour over chocolate and let sit 2- 3 minutes. Whisk until smooth. Refrigerate about 10 minutes, or until it starts to set (pull out before it gets too firm).
5. When cupcakes have cooled, use an apple corer to remove the center of a cupcake, about 1 1/2-inches deep (be careful and don’t go all the way to the bottom). Fill with a teaspoon of ganache and plug the top with about half of the removed cupcake core. Frost cupcakes with espresso buttercream (recipe below).

espresso buttercream

1. Combine espresso powder and vanilla in a small bowl and stir until fully dissolved. Set aside.
2. Sift powdered sugar into a large bowl. Place butter in the bowl of a stand mixer fitted with a paddle attachment. Mix on medium speed to soften, about 30 seconds. Add all of the sifted powdered sugar (use splash guard to avoid a huge mess) and mix on low speed until it just comes together, about 3 minutes. Mixture will look very powdery at first. Scrape down sides and bottom of bowl, and mix again to incorporate any loose powdered sugar.
3. Add boiling water to espresso mixture. Turn mixer on high, immediately add hot espresso mixture, and mix until just combined, about 20 seconds. Use buttercream as is, or create additional shades. Divide buttercream into several bowls and stir in various amounts of black cocoa powder (starting with a teaspoon). Transfer to a piping bag and decorate cupcakes as desired.