Ingredients

For the Stout Chocolate Cupcakes:
• 1 cup stout (such as Guinness)
• 1 cup (2 sticks) unsalted butter
• 3/4 cup unsweetened cocoa powder (preferably Dutch-process)
• 2 cups all purpose flour
• 2 cups sugar
• 1 1/2 teaspoons baking soda
• 3/4 teaspoon salt
• 2 large eggs
• 2/3 cup sour cream
For the Whiskey Ganache Filling:
• 8 ounces bittersweet chocolate
• 2/3 cup heavy cream
• 2 tablespoons butter, room temperature
• 2 teaspoons Irish whiskey (optional)
For the Irish Cream Frosting:
• 3 to 4 cups confections sugar
• 1 stick (1/2 cup or 4 ounces) unsalted butter, at room temperature
• 1/4 cup to 1/2 cup tablespoons Baileys

Instructions

Make the Cupcakes:
1. Preheat oven to 350 degrees F and line 24 cupcake cups with liners. Bring 1 cup stout and 1 cup butter to a simmer in a heavy, large saucepan over medium heat. Add the cocoa powder and whisk until the mixture is smooth. Cool slightly.
2. Whisk the flour, sugar, baking soda, and 3/4 teaspoon salt in large bowl to blend. Using an electric mixer, beat the eggs and sour cream in another large bowl to blend. Add the stout-chocolate mixture to the egg mixture and beat just to combine. Add the flour mixture and beat briefly on low speed. Using a rubber spatula, fold the batter until it's completely combined. Divide the batter among the cupcake liners, filling them two-thirds to three-quarters of the way. Bake the cupcakes until a tester inserted into the center comes out clean, rotating them once front to back if your oven bakes unevenly, about 16-18 minutes. Cool the cupcakes on a rack completely.
Make the Whiskey Ganache:
3. Chop the chocolate and place in a heatproof bowl. Heat the cream until simmering and pour it over the chocolate. Let it sit for one minute and then whisk until smooth (if there are still pieces of unmelted chocolate after whisking for a couple of minutes, you can heat it over a double boiler, whisking constantly until it's completely smooth). Add the butter and whiskey and stir until combined.
Fill the Cupcakes:
4. Let the ganache cool until thick but still soft enough to be piped (you can put it in the fridge to speed up this process, but make sure to stir it every 10 minutes). Meanwhile, using your 1-inch round cookie cutter, an apple corer, or a small sharp knife, cut the centers out of the cooled cupcakes. You want to go most of the way down the cupcake but not cut through the bottom — aim for 2/3 of the way. Put the ganache into a piping bag with a wide tip (or a plastic bag with a corner snipped off) and fill the holes in each cupcake to the top. Technically, you're only supposed to fill the ganache to the top of the cupcake, but I allowed mine to peak, so it looked like a little hershey's kiss on top. I figured a little extra whiskey ganache didn't hurt.
Make the Irish Cream Frosting:
5. Whip the butter in the bowl of an electric mixer, or with a hand mixer, for several minutes until very light and fluffy. Slowly add the powdered sugar, a few tablespoons at a time.
6. When the frosting looks thick enough to spread, drizzle in the Baileys and whip it until combined. If the frosting is too thin, beat in another spoonful or two of powdered sugar.
7. Lastly, ice and decorate the cupcakes. I used green sprinkles to make it festive for St. Patrick's Day, but they're also pretty on their own.