Marshmallow Moon Pie Cake (Updated) – Inspired by Ben and Jerry’s ice cream flavor by Jimmy Fallon, my Marshmallow Moon Pie Cake will make you think you’re biting into the classic junk food treat, a Moon Pie.

Old Marshmallow Moon Cake
Nearly two years ago I created my Marshmallow Moon Cake, inspired by Ben and Jerry’s Moon Pie ice cream flavor they co-created with Jimmy Fallon. Similar to my Tonight Show Cake, I took all the flavors of the ice cream and used them to inspire each element of the cake.

In this cake you have vanilla cake layers, marshmallow filling, a graham cracker crumble and chocolate ganache. Sound familiar? It’s basically a vanilla s’mores cake!
Milk-Bar Style
In my first edition of this cake, I built the cake Milk-Bar style. I love how Christina Tosi shows off her cake layers with this technique. You can look back at my original post for instructions on how to build a cake like this – just click HERE.
New Marshmallow Moon Pie Cake
It’s been a while since I made this cake and I was eager to revisit it. It’s just so good! As I was thinking about the cake and all the elements, I felt like it was really missing a buttercream – because it was! In my first edition, there’s no buttercream with this cake. (Say it ain’t so!). I also wanted to switch things up and stack and decorate it like one of my usual cakes.

Since this is basically a vanilla s’mores cake, and I’ve already done a chocolate s’mores cake (Ultimate S’mores Cake), I decided to create a graham cracker buttercream instead of a chocolate buttercream.

Oh friends! This graham cracker frosting is a serious game changer! With a hint of cinnamon and lots of graham cracker, the flavor is just so good. I love how it brings the whole cake together.

And because this cake is so tall, I like to cut two layers down and serve the top half first and then serve the bottom two layers. You’ll get about 16 slices of cake this way.

Helpful Tips
- Be careful not to over bake the cake layers. Remember, when you insert a toothpick in the center of the cake, a few moist crumbs should come out. The cake continues to bake for about 5 minutes while it’s cooling.
- Everything can be made ahead of time and stored in the freezer or fridge. Bring the fillings and frosting back to room temperature before assembling the cake. Cake layers should be chilled, but not frozen, when you assemble.
- Make sure to apply a crumb coat – a thin layer of frosting that you’ll freeze on the cake for 10 to 15 minutes to lock in the crumbs. This ensures you don’t get any crumbs in your final coat of frosting.
- If you notice that you have to push really hard on your frosting to spread it around the cake, it’s the wrong consistency. You shouldn’t ever have to apply too much pressure to spread the frosting. If you have stiff frosting, rebeat it in the mixer and add a little extra heavy whipping cream.
Hi Courtney – can you direct me to a reference, or tell me here, how to break down this cake into steps/days in advance? Obviously I know I can make the cake layers ahead of time, but what about the other elements listed?
You can make the graham cracker crumble ahead of time and store in an airtight container. Same for the frosting and marshmallow filling. The ganache I would make same day of assembly.
AMAZING cake! Lots of steps, but nothing tough. The frosting and the marshmallow filling is out of this world good. Just wondering, is it possible to save the marshmallow filling? I had a lot left over, but not sure for how long (or if) it can be stored.
It will only be good for a little and then it wills start to seperate.
Hi Courtney!! First, I have made a few of your cakes and they are always delicious.
For this one, my cake layers came out surprisingly flat. I am wondering if it was because I actually weighed the ingredients using a scale and not using cup measurements. The 3 cups of cake flour I didn’t use a cup measurement but instead my kitchen scale to mass out 374 g of cake flour. Could this be what went wrong?
Thanks for your help. 🙂
-Kerry
It could be that you overmxied or some of your ingredients were old!
I’m trying to decide between this cake and your milk bar version. I love the look of the milk bar version, but love the addition of the buttercream in this one. Do you think it would work to stack this cake “milk bar style” but add the buttercream between the cake layers instead of on the outside? If so, what order would you suggest adding the fillings?
Thanks <3
Why not! Do the buttercream first then marshmallow.
Should I store the graham cracker crumbs in the fridge once toasted or on the counter if I make them ahead of time?
Will the cake layers get dry if I make the day ahead of refrigerate?
Graham crackers sealed on the counter is fine. And then the cake should be in the freezer! Fridge will dry out.