Baking the Cupcakes:

1. Preheat oven to 350°F and line two 12-count muffin tins with butter or paper liners.
2. In a large bowl, whisk together the flour, cocoa powder, baking soda, and salt.
3. Using a stand mixer or hand mixer, beat the butter, granulated sugar, and brown sugar until light and fluffy.
4. Add one egg at a time, beating until fully incorporated. Stir in the vanilla extract.
5. Mix in the sour cream until combined.
6. With the mixer running, slowly pour in the Guinness.
7. Sift the dry ingredients into the batter and stir gently until fully mixed, ensuring no flour pockets remain.
8. Divide the batter evenly into muffin cups (about ¼ cup per cupcake).
9. Bake for 20–25 minutes or until a toothpick inserted in the center comes out clean.
10. Let the cupcakes cool on a rack before frosting.

Whipping Up the Baileys Frosting:

1. In a mixing bowl, beat the cream cheese, butter, and confectioner’s sugar until light and fluffy.
2. Slowly drizzle in the Baileys, adjusting the amount to taste.
3. Beat until smooth and fully incorporated.
4. Transfer frosting to a piping bag or ziplock bag and frost the cooled cupcakes.