Chocolate Beer Cupcakes With Whiskey Filling And Irish Cream Icing

Ingredients

• 1 cup Irish stout beer (such as Guinness®)
• 1 cup butter
• ¾ cup unsweetened cocoa powder
• 2 cups all-purpose flour
• 2 cups white sugar
• 1 ½ teaspoons baking soda
• ¾ teaspoon salt
• 2 large eggs
• ⅔ cup sour cream
• ⅔ cup heavy whipping cream
• 8 ounces bittersweet chocolate, chopped
• 2 tablespoons butter
• 1 teaspoon Irish whiskey, or more to taste
• ½ cup butter, softened
• 3 cups confectioners' sugar, or more as needed
• 3 tablespoons Irish cream liqueur (such as Baileys®), or more to taste