Place paper baking cups in each of 24 regular size muffin cups.
In a large bowl beat cake mix, oil, eggs and beer until combined.
Divide batter evenly among muffin cups.
Bake according to instructions on the box.
Cool completely and frost.
For the Frosting
Place the butter in a mixing bowl and beat until creamy.
Gradually add the powdered sugar, ½ cup at a time until it reaches desired consistency.
Add the Bailey's and combine.
Notes
Careful with Consistency: When preparing the frosting, gradually add powdered sugar to achieve the desired consistency. Too little sugar can result in a runny frosting, while too much can make it overly sweet. Aim for a smooth and spreadable texture that holds its shape when piped onto the cupcakes.
Incorporate Flavors Thoughtfully: Adjust the amount of Bailey's Irish Cream in the frosting according to your preference for its flavor intensity. Start with a smaller amount and gradually add more to taste. Remember that the alcohol content in Bailey's can also affect the consistency of the frosting, so balance flavor and texture accordingly.
Optimal Baking Conditions: To ensure the cupcakes bake evenly and maintain their moistness, avoid overmixing the batter and filling the muffin cups about two-thirds full. Additionally, keep an eye on the baking time and test for doneness with a toothpick inserted into the center of a cupcake—it should come out clean or with a few moist crumbs attached.