> 1 (15.2 oz) box devil's food cake mix
> 1 (3.9 oz) box instant chocolate pudding mix
> 1/2 cup Guinness ® Beer
> 1/2 cup canola oil
> 3 large eggs
> 1 1/2 sticks (3/4 cup) unsalted butter, room temperature
> 4 cups confectioners' sugar
> 4 tbsp Bailey's™ Irish Cream Liqueur
> Green food coloring (optional)
> Green sprinkles, to decorate (optional)
Preheat oven to 350°F. Line 2 baking sheets with parchment. In a large bowl, using a hand mixer or stand mixer, beat together the cake mix, pudding mix, Guinness, and oil. Beat in the eggs, one at a time, until combined, scraping down the sides of bowl. Beat 2 min., until smooth.
Scoop 2-tbsp mounds of batter onto prepared baking sheets, 2 inches apart. Bake 10–13 min. Cool completely.
In a large bowl, using a hand mixer or stand mixer, cream together the butter, confectioners’ sugar, and Bailey’s. If desired, add enough green food coloring for a light green color.
Transfer frosting to a resealable plastic bag or pastry bag fitted with a small pastry tip (¼ inch). Pipe filling onto flat sides of half of cakes. Top each with another cake to sandwich the frosting. If desired, add the sprinkles to a small plate and roll the edges of the frosting in sprinkles.