With a graham cracker crust, moist chocolate cake, marshmallow fluff buttercream, and milk chocolate ganache, this Three Layer S’mores Cake is the ultimate cake for s’mores lovers!

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Happy National S’mores Day!

Of all the silly, made-up food holidays, National S’mores Day is one of the few I’m willing to celebrate (along with Pi Day, of course!). S’mores are delicious and such a fun nostalgic childhood treat.

Of course, these days, I live in the middle of the city, so instead of camping and outdoor bonfires, we eat our s’mores in other forms.

Fortunately, the classic combination of graham crackers + marshmallows + chocolate is delicious in so many different ways… like this incredible three-layer s’mores cake!

A crispy graham cracker layer, my favorite chocolate cake recipe, and marshmallow fluff buttercream, topped with milk chocolate ganache and toasted marshmallows.

Just please don’t make me wait until next August 10th to make this cake again!

S’mores Cake Components

There are a lot of components going into this cake, so let’s discuss them. (But don’t worry, it comes together as quickly as most other layer cakes!)

1. Graham Cracker Crust: The bottom layer of each cake is a graham cracker crust. That’s right – we’re baking an entire layer of graham cracker crust in the bottom of a cake pan, then pouring the cake batter on top. This ensures an even distribution of crispy graham crackers across the entire cake.
2. The Best Chocolate Cake: Next up, my favorite chocolate cake – extra moist and extra chocolatey!
3. Marshmallow Buttercream Frosting: In between each layer and outside the cake, we’ll use a buttercream frosting made with marshmallow fluff to add marshmallow flavoring without the stickiness of melted marshmallows!
4. Milk Chocolate Ganache: You can, of course, use any type of chocolate for the ganache, but to stick with the class s’mores flavor, I like to use milk chocolate. The ganache gets poured over the top of the cake.
5. Toasted Marshmallows: Top the cake with miniature marshmallows, which will be toasted (or burnt – your choice!) just like a real s’more.
6. Extra Graham Crackers for Decorating: Optional, of course, but I pressed graham crackers along the perimeter of the cake and in the toasted marshmallows on top. Bonus: between the ganache poured on top of the cake and the graham crackers along the edge, you don’t have to worry about perfectly smooth frosting!

Graham Cracker Crust

The one part of this s’mores cake that is a little extra work compared to a typical layer cake is the graham cracker crust.

We’ll make it just like we would a graham cracker pie crust, combining crushed graham crackers, butter, and a little sugar.

Add one-third of this mixture to each of the prepared cake pans, then press the crumbs down to form a compact, flat layer. Bake for 10 minutes to help set the layer, then set aside to cool before pouring the cake batter on top.

Toasting Marshmallows Indoors

If you’re not into toasted marshmallows, you could certainly skip toasting the marshmallows on top of the cake (or skip the marshmallow decorations entirely).

But really… if you don’t like toasted marshmallows, you probably wouldn’t be making a s’mores cake in the first place.

There are a few different ways to get these marshmallows on top a perfect toasty brown (or charred black, depending on your preference!)

1. Broil in the oven.  Put the cake 5-6″ underneath the broiler until the marshmallows are brown. This is my least favorite method for this cake because the broiler heats up the chocolate ganache while also toasting the marshmallows.
2. Kitchen torch/soldering torch.  Kitchen torches, also called creme brûlée torches, have a very moderate flame and will allow you to get a nice golden color. If you have a “go big or go home” motto like yours truly, you can use a soldering torch, but just be warned that this is a lot more power than you need (and why my toasted marshmallows are a little more black and a little less golden!).
3. Long-Reach Butane Lighter.  You know, the long stick-like lighters people use to light birthday candles?   Just be prepared for this to take a long time because the flame is so small.  But you won’t run the risk of burning your marshmallows – it’s just not a strong enough flame.

While we’re on the topic of toasting marshmallows for our s’mores cake, how about a little discussion about why marshmallows toast in the first place? It’s time for my favorite subject… kitchen chemistry!

Kitchen Chemistry

Marshmallows are made predominantly out of sugar, which is composed of carbon, hydrogen, and oxygen.  Carbon, hydrogen, and oxygen are the primary components of fuel — meaning a marshmallow is basically a piece of fuel, waiting to ignite, which is why it’s so easy to go from toasty brown to on fire! 

Recommended Tools to Make S’mores Cake

• 8-inch Cake Pans: Since this is a three-layer cake, I recommend having three 8-inch cake pans so all the layers can be baked at the same time.
• Food Processor: A food processor is helpful to finely crush the graham cracker crumbs into a uniform, even size.
• Mixing Bowls: This set of mixing bowls has just the right sizes for making the cake batter and the ganache.
• Bake-Even Strips: I always use the Bake-Even strips on the outside of my cake pans to prevent the top of the cake from forming a dome while baking.
• Stand Mixer: An electric mixer is helpful to make the thick buttercream frosting.
• Cake Turntable: This rotating cake stand makes decorating a cake so much easier!
• Piping Bags: Use piping bags for the chocolate ganache drizzle down the side of the cake.
• Culinary Torch: A culinary torch helps toast the marshmallows to a perfect golden brown, without heating the entire cake too much.

Tips and Tricks for The Best Three Layer S’mores Cake

1. Crush the graham crackers into tiny crumbs.  This imparts graham cracker flavor into the base while maintaining the perfect texture without large pieces of graham crackers.
2. To keep cake layers perfectly flat, use Bake Even Strips (or wet cloth soaked in water and wrapped tightly around the outside of the cake pan).
3. Use miniature marshmallows, or cut large marshmallows into small pieces.  Jumbo marshmallows are too big to toast all the way through without melting the ganache on top of the cake. Use miniature marshmallows for a gooey, melted texture.
4. For an authentic s’mores experience, use milk chocolate for the ganache.  (But of course, semisweet or dark chocolate will work as well.)
5. Prefer homemade marshmallow fluff for the frosting? Store-bought works just fine, but if you want to take it a step further, use the “marshmallow meringue frosting” recipe found here.

More S’mores Desserts:

• S’mores Babka
• S’mores Brownies
• Gooey S’mores Bars
• S’mores Cookie Cake
• S’mores Bundt Cake
• All S’mores Desserts »