Baking the Cupcakes:
- Preheat oven to 350°F and line two 12-count muffin tins with butter or paper liners.
- In a large bowl, whisk together the flour, cocoa powder, baking soda, and salt.
- Using a stand mixer or hand mixer, beat the butter, granulated sugar, and brown sugar until light and fluffy.
- Add one egg at a time, beating until fully incorporated. Stir in the vanilla extract.
- Mix in the sour cream until combined.
- With the mixer running, slowly pour in the Guinness.
- Sift the dry ingredients into the batter and stir gently until fully mixed, ensuring no flour pockets remain.
- Divide the batter evenly into muffin cups (about ¼ cup per cupcake).
- Bake for 20–25 minutes or until a toothpick inserted in the center comes out clean.
- Let the cupcakes cool on a rack before frosting.
Whipping Up the Baileys Frosting:
- In a mixing bowl, beat the cream cheese, butter, and confectioner’s sugar until light and fluffy.
- Slowly drizzle in the Baileys, adjusting the amount to taste.
- Beat until smooth and fully incorporated.
- Transfer frosting to a piping bag or ziplock bag and frost the cooled cupcakes.