It's a busy week this week, so I thought I would kill two birds with one stone with this post. Today is Pi Day (3.14)  (get it? Pie? HA!) and Thursday is St. Patrick's Day, so what better way to celebrate both than with Guinness and Bailey's Irish Cream Whoopie Pies!

I've made this recipe before but in cupcake form. It totally rocked my world and these whoopie pies do not disappoint. I basically took the cupcake recipe and added some flour and baking powder. I think they turned out pretty well.

Guinness and Bailey's Irish Cream Whoopie Pies
recipe originally for cupcakes adapted from Annie's Eats, as seen on Smitten Kitchen

For the Guinness whoopie pies:
1 cup Guinness stout
16 tbsp. unsalted butter
¾ cup unsweetened cocoa powder
2 1/2 C. all-purpose flour
2 1/4 C. sugar
1½ tsp. baking soda
1 tsp. baking powder
¾ tsp. salt
2 large eggs
2/3 C. sour cream

For the filling:
16 T. (2 sticks) unsalted butter, at room temperature
4 cups confectioners’ sugar, sifted
6-8 T. Bailey’s Irish cream

Preheat oven to 350. Lightly grease baking sheets or line with parchment paper or a silicon baking sheet or if you have a whoopie pie pan, like I do, spray each well with pan release such as Pam.

Combine the stout and butter in a medium saucepan over medium heat.  Add the cocoa powder and whisk until smooth.  Remove from the heat and allow to cool slightly.

In a large mixing bowl, combine the flour, sugar, baking soda, baking powder and salt.  In the bowl of an electric mixer fitted with the paddle attachment, beat together the eggs and sour cream to blend.  Add the stout-butter mixture and beat just to combine.  Mix in the dry ingredients on low speed just until incorporated.

Using an ice cream scoop or large spoon, drop dough onto prepared baking sheets and bake for 7-9 minutes. Let cookies sit for 3-5 minutes on baking sheet then transfer to wire rack for cooling. Once cooled,  take the Irish buttercream filling and make sandwiches with the cookies.

To make the filling, place the butter in the bowl of a stand mixer fitted with the paddle attachment.  Beat on medium-high speed until light and fluffy, about 2-3 minutes.  Gradually add the powdered sugar until it is all incorporated.  Mix in the Bailey’s until smooth.  Add more if necessary until the buttercream has reached a good consistency for piping or spreading. If the consistency of the buttercream is still not spreadable and you are worried about adding too much Bailey's, you can add a teaspoon or so of milk (not too much) to get it to spreadable consistency.