Guinness Stout Whoopie Pies with Baileys Frosting

Steps

1. Preheat oven to 350°F. Line 2 baking sheets with parchment. In a large bowl, using a hand mixer or stand mixer, beat together cake mix, pudding mix, Guinness and oil until combined. Beat in eggs, one at a time, until combined, scraping down the sides of bowl. Beat until batter is smooth, 1–2 minutes.
2. Scoop 2-tablespoon mounds of batter onto prepared baking sheets, spacing 2 inches apart. Bake until cakes spring back slightly when gently pressed, 10–13 minutes. Cool completely.
3. In a large bowl, using a hand mixer or stand mixer, cream together butter, confectioners’ sugar and Baileys until light and fluffy, starting on low speed and gradually increasing to medium-high. If desired, add enough green food coloring to tint frosting a light green color.
4. Transfer frosting to a resealable plastic bag or pastry bag fitted with a small pastry tip (¼-inch wide). Pipe filling onto flat sides of half of cakes. Top each with another cake to sandwich the frosting. If desired, add sprinkles to a small plate and roll the edges of the frosting in sprinkles.