St. Patricks Day Dessert: Irish Car Bomb Brownies

Why I Love This Recipe
Named for one of favorite drinks! I love the flavor combination of chocolate and Irish cream, so this was a no-brainer for tomorrow's St. Patrick's Day Party!
Ingredients You'll Need
2 boxes Hershey's double chocolate brownie mix
1 c. vegetable oil
1/4 cup Guiness stout
4 eggs
For frosting: 2 cups confectioners sugar
1 stick butter, softened
1/4 c. Bailey's Irish cream
1/2 tsp. Jameson's Irish Whiskey (optional, this is only for you hard core Irish!)
Cocoa Powder for garnish (or green sugar!)
Directions
Preheat oven to 325 degrees and grease a 9x13 inch glass baking dish.
Blend brownie mix, oil, stout, and eggs with a large spatula until just combined, pour into pan.
Bake for 45 minutes or until toothpick inserted in center comes out clean.
Cool completely in pan before cutting into squares (at least 3 hours!)
Beat butter, confectioners sugar, and 1/2 Bailey's until blended.
Slowly add whiskey and remaining Bailey's while beating until desired consistency is reached. Frosting should be thick and fluffy.
Top brownie squares with a dollop of frosting and dust with cocoa powder.