The peppermint filling makes these whoopie pies ultra flavorful and festive, and perfect for St. Patrick’s Day, Christmas, or really any special gathering.
Is there anything better than sandwich cookies and a glass of milk?! I hope you love these Chocolate Peppermint Whoopie Pies as much as we do.
How to Make Mint Chocolate Whoopie Pies
What is a Whoopie Pie?
Whoopie pies are something of a misnomer. The outer pieces of a Whoopie Pie are neither pie, cake, or cookie. Their texture is somewhere between the latter two.
My Peppermint Chocolate Whoopie Pies recipe sandwiches rich, moist chocolate fudge cakes sandwiched together with a creamy mint-flavored buttercream frosting. They balance each other out perfectly, for a mouth-watering yet not sickly sweet treat.
Ingredients for Mint Chocolate Whoopie Pies:
- All-purpose flour – Measured correctly. If you add too much flour, you may end up with dense, hard Mint Chocolate Whoopie Pies.
- Cocoa powder – We’re using Dutch-processed cocoa powder here. More on that below.
- Baking soda – Check out my Baking Soda vs. Baking Powder article to learn about the surprising differences between these two leaveners, and learn how to test if your leaveners are still fresh.
- Salt – I prefer to use fine sea salt instead of table salt. Learn more about the differences between types of salt here.
- Butter – Always use unsalted butter in baking. It’s important that your butter is at a cool room temperature, not too warm or greasy otherwise your whoopie pies may spread too much.
- Light Brown Sugar – For additional moisture and depth of flavor. Sugar does much more than simply sweeten your baked goods! Read more about the role of sugar in baking here.
- Egg – One egg, at room temperature. Be sure to use a large egg, about 56 grams in shell.
- Vanilla extract – For flavor.
- Buttermilk – This gives the Mint Chocolate Whoopie Pies a delightful tang to help balance the sweetness, and together with the baking soda, helps create a lovely light, fluffy texture. More on this below.
Ingredients for Mint Buttercream Filling:
- Powdered sugar – Don’t use anything but powdered sugar! Read more about the type of powdered sugar I like to use below.
- Butter – This creates the base of the creamy filling.
- Sea salt – To balance out the sweetness.
- Peppermint extract – For the mint flavoring! Don’t use mint or spearmint extract, otherwise your buttercream might taste a bit like toothpaste!
- Heavy cream – To smooth out the frosting so it’s creamy and easy to work with.
- Green gel food coloring – optional, to color the frosting.
Instructions for Making Mint Chocolate Whoopie Pies:
- Mix the dry ingredients. Sift the flour, cocoa powder, baking soda, and salt into a medium bowl and whisk to combine. Set aside.
- Cream the butter and sugar. In the bowl of a stand mixer fitted with the paddle attachment (or a large mixing bowl and using an electric hand mixer), beat the butter and brown sugar on low speed until combined. Increase to medium-high speed and beat for 3 minutes, or until light and fluffy. Scrape down the sides of the bowl.
- Add the egg and vanilla. Beat on medium-high speed for another 3 minutes, or until very well combined. Scrape down the sides with a rubber spatula.
- Alternating, add the buttermilk and the dry ingredients to the butter mixture. Add half of the flour mixture then half of the buttermilk to the batter and beat on low until combined, scraping down the sides and bottom of the bowl as necessary. Pour in remaining buttermilk and flour, beating until combined.
- Portion out. Use a medium 1 ½-tablespoon spring-loaded scoop to drop mounds of batter onto prepared baking sheets (cookie sheets lined with parchment paper), spacing 2 inches apart.
- Bake. Bake Whoopie Pies in a 375°F oven for 11 minutes, or until they spring back slightly when pressed gently and appear dry on top. Allow to cool on pans for 5 minutes before moving to a wire rack to cool completely.
- Make the buttercream frosting. In the bowl of an electric mixer (or a large bowl), mix the powdered sugar and butter on low speed until well blended. Increase the speed to medium and beat until the mixture is completely smooth. Add the salt, peppermint extract, and cream and beat on medium for 1 minute. Add in green gel food coloring, if desired, and beat until evenly colored.
- Assemble. Use a medium 1 ½-tablespoon spring-loaded scoop to dollop mint buttercream on the flat side of half the Whoopie Pies. Alternatively, use a piping bag to pipe approximately 1 ½-tablespoons of filling on the flat side of half the Whoopie Pies. Sandwich gently with the remaining Whoopie Pies.
Do I Have to Use Dutch-Processed Cocoa Powder in These Mint Chocolate Whoopie Pies?
I prefer Dutch-process cocoa powder for this recipe for its delicious flavor, deep chocolate color, and higher fat content which helps prevent any dryness. You can learn more about the differences between cocoa powders here. You CAN use regular natural unsweetened cocoa powder instead. Just note your Whoopie Pies may be lighter in color and slightly dryer in texture.
Although Dutch-process cocoa is typically paired with baking powder, I actually use baking soda in this recipe. This works because the buttermilk activates the baking soda. More on that below.
You can find Dutch-process cocoa at your local grocery store or many gourmet food stores, like Penzeys, Whole Foods, Sur la Table, and Williams Sonoma. I actually order a big container on Amazon because it’s such a great value!
Do I Have to Use Real Buttermilk in Mint Whoopie Pies?
Buttermilk works best in this recipe to provide rich and tender ‘cakes.’ We need it not only for flavor and moisture, but to help activate the baking soda for light fluffy cakes. I would not recommend using a buttermilk substitute. You can learn more about the science of buttermilk, and see baked goods made with buttermilk substitutes, in my Buttermilk 101 article.
What Type of Powdered Sugar is Best for the Peppermint Buttercream Filling?
For the absolute smoothest buttercream for these Mint Whoopie Pies, I recommend investing in organic powdered sugar that contains tapioca starch instead of cornstarch because it dissolves much more readily – so no grittiness! It’s still necessary to sift the confectioners’ sugar after measuring it, and before adding it into the mixing bowl. This will ensure no pesky lumps and clumps ruin the smoothness of your frosting. This is the brand of organic powdered sugar I usually use.
Organic powdered sugar is more pricey so if that’s not in budget, go ahead and use conventional powdered sugar.
Tips for the Buttercream Frosting for Mint Chocolate Whoopie Pies:
- Feel free to adjust the amount of powdered sugar to cream until you get the consistency of frosting you prefer.
- If using green food coloring, I much prefer gel coloring. It allows you to use just a small amount for an intense color. I like the Americolor brand the best. Start with a very small amount and add more as you blend.
- Be sure to use peppermint extract to flavor the buttercream. Do not use mint extract or spearmint extract unless you want your Whoopie Pies to taste like toothpaste.
How to Portion Out Whoopie Pies & How to Fill Them:
This Whoopie Pie batter is similar in consistency to a very thick cake batter. My favorite way to portion these out is to use my medium cookie scoop (1.5 tablespoons), which not only creates perfectly consistent Whoopie Pies that bake evenly, but it also makes quick work of portioning out the batter/dough. The same scoop also makes easy work of adding the mint buttercream, but if you prefer, you can pipe it on to half the Whoopie Pies using a disposable piping bag and a large round tip, before sandwiching with the other half of the Peppermint Chocolate Whoopie Pies.
You can use an ice cream scoop if you don’t have a cookie scoop to portion out the batter, but please note that this will alter the bake times, depending on the size of the ice cream scoop.
How to Decorate Mint Chocolate Whoopie Pies:
I think these Whoopie Pies are pretty with a light green frosting swirled in the middle, but you can decorate these further if you like!
- Drizzle the tops of your Whoopie Pies with a little melted white chocolate
- Top with nonpareils before baking
- Roll the edges in festive sprinkles
- If you’re serving these around Christmas, roll in crushed candy canes, peppermint candies, or even finely chopped Andes mints, for a delicious chocolate mint flavor
How to Store Peppermint Chocolate Whoopie Pies:
Store at room temperature in an airtight container for up to a day, or in the fridge for up to 4 days. If transporting, chill the Peppermint Chocolate Whoopie Pies in the fridge for at least an hour before transporting, as refrigeration makes them firmer and less fragile. Best served at room temperature so the buttercream filling has time to soften.
Can you Freeze Mint Chocolate Whoopie Pies?
Yes! I recommend placing the Peppermint Chocolate Whoopie Pies on a baking sheet in a single layer and freezing for an hour or so, until just solid enough to prevent them from sticking together. Then, simply place in a ziptop bag or an airtight container in the freezer for up to 1 month. Thaw for a few hours or overnight in the fridge or at room temperature (either is fine) before serving.