Chocolate Whoopie Pie Monsters

Made with cake mix, these Chocolate Whoopie Pie Monsters turn a basic chocolate whoopie pie recipe into a fun Halloween treat that the whole family will love. Stuffed with a creamy marshmallow filling, these monster treats are hard to resist!

These Chocolate Whoopie Pie Monsters are so fun and easy to make, perfect for Halloween parties or just a special spooky treat. I made the chocolate whoopie pies using the Betty Crocker recipe, as it’s easy and there’s no need to invent the wheel.

But while Betty Crocker stuffs their whoopie pies with frosting, I chose to make a creamy filling made with marshmallow fluffy instead. It’s sweet and smooth and much fluffier than frosting. I think the marshmallow pairs nicely with the soft, cake-like chocolate cookies.

To turn these cake mix whoopie pies into monster treats, I added green food colouring to the filling and added some sprinkles on the edges. Googly eyes turn them into the cutest monsters you might see this Halloween! 

What is a Whoopie Pie? (And Where Did They Come From?)

Despite the name, whoopie pies are not actually pies at all. They are essentially two fluffy, cake-like cookies stuffed with a sweet, creamy filling – usually buttercream frosting or marshmallow fluff. The most common ones are chocolate whoopie pies, though they can be made in virtually any flavour.

Whoopie pies are very popular in the Northeast USA, including the New England states and Pennsylvania. Maine has declared whoopie pies to be their “Official State Treat” and the 3^rd Saturday in June to be Whoopie Pie Day. Many states hold Whoopie Pie Festivals and baking contests. (So clearly, they take this dessert quite seriously!)

There is much disagreement over the actual origin of whoopie pies. Pennsylvania, Maine, New Hampshire, and Massachusettes all claim that this beloved treat originated in their state.

One of the most popular stories is that the whoopie pie was invented by the Amish wives in Pennsylvania, using leftover cake batter and frosting. However, the first commercially sold whoopie pies were sold in Maine, at Labadie’s Bakery, in 1918 or 1925 (depending on who you ask). The Berwick Baking Company in Boston also holds claim to being the first to invent or sell these treats.

And while we will likely never know the real origin of whoopie pies, they are an absolutely addicting treat you must try. 

Ingredients & Substitutions

• Cake mix – These chocolate whoopie pies start with Betty Crocker Super Moist Devil’s Food cake mix for a rich flavor. 

• Cake mix add-ins  – As with most cake mix recipes, you’ll need to add water, vegetable oil, and eggs to the mix.

• Chocolate pudding – Instant pudding and pie filling mix adds more chocolate flavor and helps to thicken the batter a bit.

• Unsalted butter – Creamed with powdered sugar to create the base of the filling.

• Powdered sugar – Sweetens the marshmallow filling and helps create a smooth texture.

• Salt – Helps to balance out the sweet ingredients and enhances the flavors.

• Marshmallow fluff – The star of the filling! Sweet, sticky, and so yummy.

• Green food colour & sprinkles – Adds the Halloween flair to these cake mix whoopie pies.

• Googly eyes – These are optional but are what turns this easy recipe into a monster treat for Halloween. 

How to Make Chocolate Whoopie Pie Monsters

These monster treats begin by following the original Betty Crocker whoopie pie cake mix recipe. Start by preheating your oven to 350°F and lining your cookie sheets with parchment paper.

Combine all of the cookie ingredients with an electric mixer. Mix on low until moistened then beat on high speed for one minute. This adds some air to the batter giving it some lift.

Transfer the batter into a resealable plastic bag. Seal and cut a small hole in one of the bottom corners. 

Pipe the batter into 36 circles of equal size. Be sure to allow an inch between each cookie as they will spread.

Bake the cookies for 10 to 12 minutes. Cool on the sheet for 2 minutes, then transfer to a cooling rack. Don’t get to ahead of yourself and try and move them while they are piping hot because they will be sticky and very very soft.

Allow the cookies to cool completely before adding the marshmallow filling. 

To make the filling, beat the butter with a hand mixture until creamy. Gradually mix in the powdered sugar, until smooth and creamy. Add in the vanilla and salt. Beat until blended.

In a separate bowl, add the marshmallow fluff and green food colouring. Mix until combined. (The fluff should all be your desired shade of green. Add more food colouring if necessary.)

Add the marshmallow fluff mixture to the butter mixture. Blend until combined. 

To assemble the cookies, transfer the marshmallow filling to a large piping bag. Pipe over half of the whoopie pie tops/bottoms, making sure to leave space along the edges.

Top each frosted cookie with an unfrosted one.

Place in the fridge or another cool place, in a single layer, for about 5 minutes.

Once they are firm enough to handle, roll the edges of each whoopie pie gently in the green sprinkles and add the googly eyes. 

Tips for the Best Cake Mix Whoopie Pies:

• Cool the cookies before frosting. Make sure to let the cookies completely cool before frosting or they will be very messy to deal with.

• Leave about a 1/4 inch area around the edge of each cookie free from frosting. This way when the tops are added the frosting has a little room to spread.

• Don’t place the top directly over the bottom. Place the tops slightly off centre and tilted so that it looks like the monster is peaking out from under his cookie hat.

• Before adding sprinkles be sure to chill the assembled whoopie pies. The frosting is very soft so if they are not firm enough the frosting may spill out when trying to roll in the sprinkles.

• Be sure not to stack these cookies. The cookie dough is very soft and airy so if stacked they may stick together and tear when you try and pull them apart.

Chocolate Whoopie Pie Variations

• Don’t make them monsters at all. Without the green dye, sprinkles and dye, these are a simple chocolate whoopie cookie.

• Change the colour of the filling. Orange and purple are great options for Halloween or you could do red for Christmas or Valentine’s Day or any other colour you prefer. 

• Try another cake mix other than chocolate. While whoopie pies are traditionally made with chocolate cake, they can also be made with pretty much any other cake mix desired. Vanilla, strawberry, spice cake, and red velvet are all tasty options.

• Add some flavour to the filling. For extra flavour in these chocolate whoopie pies, add a drop or two of your favorite extract to the marshmallow mixture.

• Turn them into witches’ hats. For a different Halloween twist, add a Hershey’s kiss to the top and secure with a little marshmallow fluff to create a witch’s hat. 

• Turn them into spiders. For another spooky twist, stick some licorice into the side of the filling to turn these monsters into spiders. 

Can I Use a Different Filling?

Absolutely. Whoopie pies can be filled with pretty much any creamy filling or frosting. A few other popular options are buttercream icing, Swiss meringue, and even Cool Whip.

Why Are My Whoopie Pies Flat?

There are typically 2 reasons that whoopie pies don’t rise – the batter was too thin or it was overmixed. Since we’re making these whoopie pies from cake mix, and there’s no measuring of the dry ingredients required, it is likely the second option. While you do want all of the ingredients properly mixed and to beat on high for one minute, be sure to not overdo it by beating the batter for much longer than that. 

How to Store & Freeze

These chocolate whoopie pies must be stored in a cool place or the fridge. This will make them much easier to eat and keep the filling from oozing out. In a tightly sealed container, these will stay fresh for up to a week.

You can also freeze any extra whoopie pies. Just individually wrap each one in plastic wrap. Freeze for up to 3 months and thaw on the counter.

More Halloween Recipes:

• Chocolate Caramel Apple Slices
• Crustless Pumpkin Pie
• Halloween Monster Apple Snacks
• Snickerdoodle Dessert Hummus