Step 1

Preheat the oven to 350 degrees Fahrenheit. Grease a 10.5x15.5-inch pan with nonstick spray or butter. Alternatively, line the pan with foil or parchment paper.

Step 2

Add brownie mix to a large mixing bowl. Make a well in the center and add the Baileys, oil, and eggs. Whisk the mixture just until it forms a smooth batter.

Step 3

Pour and spread the batter evenly into the greased pan. Bake for 20 minutes, or until a toothpick inserted into the center comes out clean. Allow brownies to cool completely.

Step 4

Meanwhile, make the frosting. Beat the softened butter with an electric mixer at medium speed until smooth and fluffy, about 1-2 minutes.

Step 5

With the mixer still running, gradually pour the Baileys. Beat until well combined. Slowly add the powdered sugar, 1 cup at a time, and beat until frosting is smooth and spreadable.

Step 6

Once brownies have cooled, spread the frosting on top. Slice into squares, serve, and enjoy!