Preheat oven according to box directions for cupcakes.
Follow the directions on the box to mix the cupcakes BUT replace the 10oz of water with 5oz coffee + 5 oz. Guinness.TIP: I use a large scoop to evenly portion cake mix into a cupcake pan. Only fill the liners about 1/2 way.
While cupcakes cook and cool, mix the frosting.
Add cream cheese, butter and salt to a stand mixer, fitted with a paddle attachment. Combine until creamy and throughly mixed together.
Add vanilla and combine again.
Slowly add the confectioners sugar, 1/2 cup at a time until completely combined.
Add 2 generous tbsp of Baileys and combine one final time.
Once cupcakes are completely cooled, pipe on the frosting. I used a bag fitted with a 4B tip but you can get creative here. I added shamrock toothpicks and gold coin sprinkles.
Now...I dare you NOT to eat that left over frosting!