When the days are warm and the evenings are cool, everyone slows down after a busy day to relax around a campfire while the sun sets and the light turns golden, I can totally get behind an ooey, gooey, sticky s’more. Marshmallows on their own are not that interesting, unless they’re homemade, which are much tastier than store-bought. But something sort of magical happens when a hot, toasty, melty marshmallow is squished between two graham crackers with a few squares of sweet chocolate. I’ve wanted to make a high altitude s’mores cake with these iconic flavors for such a long time, and I couldn’t be more pleased with how this cake turned out. There’s three layers of buttery graham cake, homemade marshmallow fluff, and rich chocolate buttercream, and they all come together perfectly in this delicious cake.
Looking for more recipes like this one? You’ll love these s’mores chocolate chip cookie bars, s’mores no churn ice cream, and key lime pie cupcakes.
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What’s in a S’mores Cake?
Of course, the three main components of a s’more are graham crackers, chocolate and marshmallows. So for our s’mores cake today, we have a delicious graham cake, filled with fluffy homemade marshmallow fluff, frosted with rich chocolate buttercream.
Graham Cake.
It’s interesting that most s’mores cake recipes on the internet start with a chocolate cake, with just a few crumbled graham crackers sprinkled here and there. But I thought that the cake should be a graham cake, to really let the flavor of the graham crackers shine.
So I used a butter-based cake recipe, with brown sugar and buttermilk for moisture, and a little cinnamon to complement the crushed graham crackers that I substituted for some of the flour. The cake baked up so moist and soft, slightly dense, and tasted just like a graham cracker but in cake form.
Homemade Marshmallow Fluff.
Next, the marshmallow. I wanted to fill the cake with some sort of marshmallow cream or frosting, and considered using store-bought marshmallow fluff. And you certainly can use store-bought marshmallow fluff if you don’t feel inclined to make your own. But I really wanted to make the extra effort to use a homemade meringue.
The marshmallow meringue isn’t difficult to make. It’s made of just egg whites and sugar, with a little cream of tartar for stability and vanilla for flavor. But it does involve first heating the egg whites and sugar until the sugar is dissolved, and then whipping it for a very, very long time (15 minutes), until cooled and thick. So if you don’t have a stand mixer to do all the whipping for you, then I wouldn’t recommend attempting it without.
The meringue was so light and fluffy, sticky but pliable enough to spread with a knife, and made the perfect gooey marshmallow filling between the cake layers.
Chocolate Buttercream.
The best part of a s’more – in my opinion – is the chocolate. And while sweet Hershey’s milk chocolate is the classic flavor, I prefer dark chocolate. So I made a batch of my perfect American buttercream, with dark, Dutched cocoa powder. What I love so much about chocolate buttercream is that, since the cocoa powder replaces some of the powdered sugar, its flavor is deeper, less sweet, and just deliciously chocolatey.
So there is such a thing as graham flour, but today’s s’mores cake recipe simply calls replacing some of the flour with very finely crushed graham crackers.
Instructions
Beat the butter and sugar.
This recipe uses the standard creaming method of mixing ingredients. So you’ll start by beating butter with granulated sugar and dark brown sugar for about 8-10 minutes. This lightens the mixture and incorporates air, making for a light and tender cake crumb.
Add the eggs.
Next, beat in the eggs, one at a time, then the vanilla extract.
Sift the dry ingredients.
Now sift together the flour, crushed graham crackers, baking powder, salt and cinnamon.
Mix the batter and bake.
Lastly, add the sifted dry ingredients to the batter, alternating with the buttermilk. Divide the batter between the pans and bake.
How to Make Homemade Marshmallow Fluff
Making homemade meringue or marshmallow fluff involves two main steps. First, you’ll need to heat the egg whites and sugar, both to dissolve the sugar, and also to heat the egg whites to a safe temperature. Second, you’ll be whipping the egg whites and sugar with cream of tartar and vanilla extract until stiff peaks form. You will need a stand mixer to make your marshmallow fluff.
- First, ensure that all your equipment – mixing bowls, whisks, spatulas, etc – are scrupulously clean, with no traces of oil or fat.
- Set up a double boiler, by filling a saucepan with a few inches of water and setting a metal bowl over the top so that it sits on top of the pan, but does not touch the water. Bring the water to a simmer.
- In the bowl, whisk together the egg whites and sugar. Heat the egg whites and sugar in the bowl set over the simmering water, whisking occasionally, until the sugar is completely dissolved (you should no longer feel any grains of sugar with your finger) and the mixture reaches about 150 degrees F.
- Scrape the mixture into the bowl of your stand mixer. With the whisk attachment, beat on medium speed until foamy, then add the cream of tartar. Beat on medium/high until the mixture is thick and ribbony. Add the vanilla, and continue beating until stiff peaks form, and the meringue is no longer warm. Altogether, you’ll beat the meringue for about 15 minutes.
- Scrape the meringue into another bowl, covered tightly with plastic wrap, so you can free up the bowl for your stand mixer, and set the meringue aside while you make the buttercream.
- The meringue can also be made one day in advance, stored in an airtight container and refrigerated until needed.
Assembling Your Cake
Once your cake is cooled and your marshmallow fluff is ready, whip up some luscious, fluffy chocolate buttercream, and you’ll be ready to assemble your cake.
While filling and stacking the cake layers with the meringue, I sprinkled on a little extra crushed graham crackers and chopped dark chocolate. Then I frosted the whole cake with swirls of chocolate buttercream.
The most fun part was swirling more of the meringue around the cake for a beautiful, chocolate marshmallow swirly effect. Every bite of the finished cake tasted like the best s’more I’ve ever eaten.
Frequently Asked Questions
Will store bought marshmallow fluff work?
Yes, you can use store bought fluff instead of homemade.
Can I substitute graham flour for the crushed graham crackers?
I’m not sure, I haven’t tried it.
How do I make a smaller version of this cake?
Cut the cake recipe in half and bake in three 6-inch cake pans. Make 2/3 of the buttercream recipe for a smaller cake.
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High Altitude S’mores Cake
All recipes on Curly Girl Kitchen are developed for high altitude at 5,280 feet. See FAQs for adjusting to higher or lower elevations.
Equipment
- Stand Mixer
Ingredients
Graham Cake
- 1 cup unsalted butter, softened to room temperature
- 1 cup granulated sugar
- ¾ cup dark brown sugar, lightly packed
- 4 large eggs
- 2 tsp vanilla extract
- 2 ¼ cups cake flour or all-purpose flour, spooned and leveled
- ¾ cup finely crushed graham cracker crumbs (original or cinnamon)
- 3 ½ tsp baking powder
- 1 tsp coarse Kosher salt (if using table salt, use half the amount)
- 1 tsp ground cinnamon
- 1 ¾ cups whole buttermilk, room temperature
Meringue or Marshmallow Fluff
- 3 large egg whites
- 1 cup granulated sugar
- ¼ tsp cream of tartar
- 1 tsp vanilla extract
Chocolate Buttercream
- 1 ½ cups unsalted butter, softened to room temperature
- 2 ⅓ cups powdered sugar
- ⅔ cup unsweetened Dutch-processed cocoa powder
- 1 tbsp meringue powder (optional)
- 1-2 tbsp instant espresso powder (optional)
- ¼ tsp coarse Kosher salt (if using table salt, use half the amount)
- 1 ½ tsp vanilla extract
- 2-3 tbsp milk or cream, if needed for desired consistency
Extras for Filling/Decorating
- ½ cup crushed graham crackers
- ½ cup finely chopped chocolate
Instructions
Graham Cake
- Preheat the oven to 350, and spray the bottoms of three 8-inch cake pans with non-stick spray.
- In the bowl of your stand mixer fitted with the paddle attachment, beat the butter, granulated sugar and brown sugar for about 8-10 minutes, scraping the bowl occasionally, until very light and fluffy.
- Add the eggs, one at a time, beating well after each addition, and scraping the bowl down, then add the vanilla.
- In a separate bowl, sift together the flour, graham cracker crumbs, baking powder, salt and cinnamon. With the mixer on low, add the dry ingredients in three additions, alternating with the buttermilk, starting and ending with the dry ingredients. Use a large spatula to stir in any remaining streaks of flour.
- Divide the batter evenly between the pans. Bake on the center rack for about 30 minutes, until the top springs back when lightly touched, and a cake tester or toothpick comes out clean.
- Cool the cakes completely in the pans on a wire rack, covered loosely with a clean kitchen towel.
Marshmallow Fluff
- First, ensure that all your equipment – mixing bowls, whisks, spatulas, etc – are scrupulously clean, with no traces of oil or fat.
- Set up a double boiler, by filling a saucepan with a few inches of water and setting a metal bowl over the top so that it sits on top of the pan, but does not touch the water. Bring the water to a simmer.
- In the bowl, whisk together the egg whites and sugar. Heat the egg whites and sugar in the bowl set over the simmering water, whisking occasionally, until the sugar is completely dissolved (you should no longer feel any grains of sugar with your finger) and the mixture reaches about 150 degrees F.
- Scrape the mixture into the bowl of your stand mixer. With the whisk attachment, beat on medium speed until foamy, then add the cream of tartar. Beat on medium/high until the mixture is thick and ribbony. Add the vanilla, and continue beating until stiff peaks form, and the meringue is no longer warm. Altogether, you’ll beat the meringue for about 15 minutes.
- Scrape the meringue into another bowl, covered tightly with plastic wrap, so you can free up the bowl for your stand mixer, and set the meringue aside while you make the buttercream.
- The meringue can also be made one day in advance, stored in an airtight container and refrigerated until needed.
Chocolate Buttercream
- In the bowl of your stand mixer fitted with the whisk attachment, beat the butter for one minute until smooth. With the mixer on low, gradually add the powdered sugar, cocoa powder, meringue powder, espresso powder, salt and vanilla.
- Beat on medium speed for 4-5 minutes, until very light and fluffy, scraping the bowl occasionally, and adding the milk if needed for the right spreading consistency.
Assembly
- Run a sharp knife around the sides of the cooled cakes. Carefully turn one of the cakes out and place on a cake stand or serving plate. Spread a generous layer of the meringue over the cake, stopping about 1/2 inch from the edges. Sprinkle with chopped chocolate and crushed graham crackers. Repeat with another layer of cake, more meringue, chocolate and graham crackers, and the last layer of cake.
- Frost the cake all over with a thin crumb coat of the chocolate buttercream, then refrigerate for 30 minutes. Frost with a final layer of chocolate buttercream, using your icing spatula to create big swoops and swirls.
- Take the remaining meringue, and dab small amounts randomly around the cake, then use an icing spatula to gently swirl it in. Take care not to blend too aggressively, since you want to see contrasting streaks of white and brown, rather than mixing them together.
- Leftover meringue can be stored in an airtight container in the refrigerator for up to one week, or you could even pile it on top of the cake and use a brulee torch to lightly toast it for a dramatic topping.
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