Happy St. Patrick’s Day! Are you wearing green? Gleefully pinching friends and strangers alike? Stuffed full of cabbage? Drunk before noon? Reminiscing fondly about the time St. Patrick drove the snakes out of Ireland? What a weird, wonderful holiday this is.
In keeping with this solemn celebration of Ireland’s patron saint, I have made you a green dessert. As one does. These Mint Chocolate Chip Whoopie Pies fulfill all your green eatin’ needs, but the also work well throughout the whole year—any day can be a mint chocolate chip day!
These whoopie pies start with two moist, cakey sour cream chocolate cookies. They’re filled with a minty Swiss meringue buttercream that’s so creamy and rich, it tastes like ice cream. I added some very finely chopped semi-sweet chocolate, so that there are flecks of chocolate in every bite. And of course, no St. Patrick’s Day treat would be complete without a glimmer of gold, so I surrounded some of the cookies with a ring of green and gold Sixlets. The Sixlets really make the cookies pop, and I love how they look like a jeweled bracelet around the edge of the cookies.
These cookies made me feel better about being a bit of a St. Patrick’s Day scrooge this year. Asher is too young to appreciate the finer things in life, like green milk and green eggs, so we skipped a lot of my favorite childhood traditions. Also, I’m already planning on having Mexican food for lunch, and I’m pretty sure salsa is not one of the officially condoned St. Patrick’s Day food groups. But I think as long as I get my green food fix with mint chip buttercream, life is good. Have a safe and fun holiday!
Mint Chocolate Chip Whoopie Pies
For the Chocolate Cookies:
- 9 1/2 oz all-purpose flour 2 1/4 cups
- 2 tbsp unsweetened cocoa powder
- 1 tsp baking soda
- 1/2 tsp salt
- 2 oz butter at room temperature
- 9 1/3 oz brown sugar 1 1/4 cup, lightly packed
- 3 1/2 oz granulated sugar 1/2 cup
- 2 eggs at room temperature
- 1 tsp vanilla extract
- 2 oz unsweetened chocolate melted and slightly cooled
- 8 oz sour cream 1 cup, at room temperature
For the Mint Chip Frosting:
- 4 egg whites at room temperature
- 7 oz granulated sugar 1 cup
- 8 oz butter softened but still cool
- 1/8 tsp salt
- 1/2 tsp mint extract
- yellow and leaf green food coloring
- 3 oz chocolate 1/2 cup very finely chopped
- Lime green shimmer Sixlets optional
- Gold Sixlets optional
To Make the Cookies:
- Preheat the oven to 350 F, and line three baking sheets with parchment paper. In a small bowl, sift together the flour, cocoa powder, baking soda, and salt, and set aside.
- Combine the butter and both sugars in the large bowl of a stand mixer fitted with a paddle attachment. Mix on medium speed for 1-2 minutes until the sugars are mixed and well-moistened, with the texture of wet sand. Add the eggs one at a time, then add the vanilla. Add the melted, cooled chocolate and mix on low speed until combined. Scrape down the bottom and sides of the bowl.
- With the mixer running on low speed, add a third of the dry ingredients. When those are mixed in, add half of the sour cream, then continue to alternate adding the dry ingredients and sour cream, until all of the ingredients are incorporated. Scrape down the bottom and sides of the bowl once more.
- Scoop 1 1/2-inch balls of batter onto the prepared baking sheets, leaving a few inches between each cookie, as they will spread. Bake for 12-14 minutes, until the cookies are puffed and they spring back lightly when pressed with a finger. Cool on the baking sheets before filling.
To Make the Mint Chip Frosting:
- Combine the egg whites and the granulated sugar in the bowl of a large stand mixer, and whisk them together. Choose a small saucepan that lets you fit the base of the stand mixer snugly into the top of the saucepan—this is your makeshift hot water bath. (Alternately, you can use a different bowl or an actual bain marie and then transfer the mixture to a mixing bowl once it’s heated.) Add an inch of water to the bottom of the saucepan, and bring the water to a simmer.
- Place the mixing bowl on top of the saucepan, making sure that the bottom isn’t in contact with the water, and heat the egg white mixture. Whisk frequently so that the egg whites don’t cook. Continue to heat the whites until they are hot to the touch, and when you rub a bit between your fingers, you don’t feel any grittiness from the sugar. Once the whites are hot, transfer the mixing bowl to your mixer and fit it with a whisk attachment.
- Beat the whites on medium-high speed until they are no longer warm to the touch—feel the outside of the bowl, and make sure that it is around room temperature. Depending on your mixer and the temperature of your environment, this may take 10-15 minutes, or more. Reduce the speed to medium-low and add the softened but cool butter in small chunks, a tablespoon at a time, making sure to wait in between additions. It may separate or look a little gloopy at this point—fear not. Once all of the butter is added, increase the speed again and whip until it comes together and is light and fluffy. If, after 5 minutes, it hasn’t come together, refrigerate the mixing bowl for 5-7 minutes, to cool the mixture down, and whip it again.
- Add the salt, mint extract, and a few drops of yellow and green food coloring, mixing until you have a nice minty green color. Finally, add the finely chopped chocolate and stir it in with a spatula. The buttercream can be made in advance and kept at room temperature if you’re going to use it the same day, or refrigerated. If it has been chilled, let it sit at room temperature until it softens, then re-whip it to get the fluffy texture back before you use it.
- To assemble the whoopie pies, fit a pastry bag with a large star attachment. Pipe a swirl of frosting on half of the cookies, leaving a small margin at the edges. Top the cookies with a second cookie, pressing down slightly so the frosting extends to the edge. If desired, press sixlets into the frosting around the edge.