Cupcakes:
1 cup Guinness (or other stout beer)
1 cup (2 sticks) unsalted butter
3/4 cup unsweetened cocoa powder
2 cups all purpose flour
2 cups sugar
1 1/2 tsp baking soda
3/4 tsp salt
2 large eggs
2/3 cup sour cream

Ganache Filling:
8 oz bittersweet chocolate chips or coarsely chopped chocolate
2/3 cup half and half or heavy cream
2 Tbsp butter, room temperature
2 tsp Irish whiskey (optional)

Baileys Icing:
3 to 4 cups confections sugar
1/2 cup (1 stick) unsalted butter, room temperature
6-8 Tbsp Baileys, I used 8 ;-)