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We’ve made a campfire treat into a showstopping s’mores cake. It has layers of rich chocolate sponge, toasted marshmallow frosting, and crunchy biscuit crumbs that come together for a nostalgic, chocolatey delight. It’s dark and rich, the perfect celebration cake. I topped it with homemade marshmallows to top it all off – it truly is so good.
Of course, shop-bought marshmallows on top would be delicious, but if you do want to make your own, I guarantee you that homemade marshmallows are so much better and take this s’mores cake to the next level. In this post, you will find a make-ahead schedule, a troubleshooting guide, and storage tips, so your bake turns out perfectly.
Table of Contents
Why you will love this recipe:
- Toasted marshmallow, chocolate, and biscuit layers are so delicious, sandwiched together.
- Make-ahead friendly: Bake over a few days for stress-free assembly.
- Perfect for birthdays, BBQs, or cosy winter desserts.
Ingredients:
Full recipe can be found in the printable recipe card at the bottom of the post, just scroll down!
Unsweetened dark cocoa powder: I used dark cocoa powder here for a really rich, deep colour and flavour in this s’mores cake. You could just use a good-quality Dutch-process or natural cocoa.
Vegetable oil: Keeps the crumb ultra-moist, alongside the butter.
Coffee: Instant coffee works well here as you will dissolve it in 350ml boiling water.
Self-raising flour: known as self-rising flour in the US.
Double cream: known as heavy cream in some parts of the world, this is for the ganache.
Egg whites: this is for the marshmallow topping. You need 160g, which will likely be around 4 large eggs.
Substitutions and Variations:
Vegetable oil: any neutral oil works. You can also use sunflower or canola oil.
Self raising flour: if you can’t find self-raising flour where you are, you can use all-purpose (plain) flour with 2 and 1/4 teaspoons of baking powder.
Lotus biscuits: I like their caramelised flavours, but traditionally, Graham crackers or digestive biscuits make sense for s’mores. Use whatever biscuit (cookie) you like.
Here’s how to make the best s’mores cake:
Here’s a step by step guide for what you need to do, but you can find the full recipe at the bottom of the page for detailed instructions.
ONE: Heat the oven to 170C fan/190c conventional/375f/. Line 3 x 18cm cake tins with parchment. Melt the chocolate over a Bain Marie and leave to the side to cool. In a stand mixer, beat the softened butter and caster sugar together for 2 minutes until smooth and pale. Add the eggs, mixing in each one before adding the next. Drizzle in the oil while mixing.
TWO: Then pour in the melted chocolate and mix briefly to combine.
THREE: Add the flour, cocoa powder and a pinch of salt. Mix well.
FOUR: In a jug, mix 350ml boiling water with the instant coffee granules. Pour slowly into the bowl of cake batter, mixing until the batter is smooth. It will look thin – that’s normal.
FIVE: Divide the mixture between the cake tins and bake for 25-30 minutes or until a skewer comes out clean when inserted.
SIX: Finely chop the chocolate. Gently heat the double cream in a saucepan. Keep an eye on it as it can boil over easily.
SEVEN: Add the chocolate to a large, heatproof bowl and once the cream is simmering, pour it over the chocolate. Add a pinch of salt and give it a minute to melt slightly before using a whisk to mix everything together until smooth.
EIGHT: Blitz the lotus biscuits in a food processor (or bash in a sealed sandwich bag). Transfer to a bowl and mix in the melted butter.
NINE: Place sugar and egg whites into a heatproof bowl and place over a saucepan of barely simmering water. With a manual whisk, whisk until all the sugar is dissolved and you can no longer see or feel any small grains of sugar.
TEN: Once the sugar is dissolved, place this mixture into the bowl of a stand mixer and whisk until you get a thick and stiff meringue, about 10 minutes. If you don’t have a stand mixer, a handheld electric whisk will work.
ELEVEN: Place one sponge on a serving plate or cake stand. Spread a thick layer of ganache over the top. Top with biscuit crumbs and then pipe/spread on the marshmallow frosting. Top with the second sponge.
TWELVE: Cover the entire cake with the remaining ganache, smoothing the sides with a palette knife or spatula. Then swipe on little patches of the marshmallow frosting and sprinkle crumbs around the base of the cake. Top with marshmallows, mine were homemade but shop-bought is of course fine. Use a blowtorch to lightly brown the marshmallow frosting and the marshmallows for a golden toasted s’mores look.
Cooking Tips:
Make-Ahead Schedule
Day 1:
- Bake cake layers.
- Cool and wrap tightly; refrigerate or freeze.
- Make ganache and refrigerate.
Day 2:
- Prepare marshmallow frosting and biscuit crumbs.
- Assemble.
Troubleshooting Common Problems
My marshmallow frosting is runny
- Ensure the sugar fully dissolves in the egg whites before whisking.
- Whisk until stiff peaks – it should hold its shape.
- Chill briefly before assembling if the kitchen is warm.
My ganache won’t thicken properly
- Keep it in the fridge, stirring every so often to make sure it chills evenly. The longer you leave it in the fridge, the firmer it will be.
Frequently Asked Questions
The unfrosted sponge layers freeze well. Wrap each layer individually in baking parchment, then cling film, and freeze for up to 3 months. Defrost overnight at room temperature before frosting. I like to make the ganache fresh for best results but it does keep in the fridge for a few days. Just bring it to room temperature before trying to spread it.
You can use shop-bought marshmallow fluff in this s’mores cake, but it is much thicker so it won’t spread as well on the cake, but it can be done.
Use a 50–70% dark chocolate for ganache – it balances the sweetness from the marshmallow and biscuit. I wouldn’t use milk chocolate, which can make the cake too sickly.
Yes, you can make cupcakes. Just divide the batter among 18 cupcake cases. Bake for 15-20 minutes. Smooth on the chocolate ganache, pipe on marshmallow frosting and sprinkle with biscuit crumbs.
Place the cake under a very hot grill (broiler) for 20-30 seconds, keeping the oven door slightly ajar and watching closely. Any longer and you’ll melt the ganache so it must be really brief and really hot.
Other recipes you might enjoy:
If you liked this s’mores cake recipe, you will love my Matilda chocolate layer cake, my chocolate orange cake or my pistachio & raspberry cake.
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Chocolate Mud Cake with Malted Whipped Cream
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If you tried this S’mores Cake or any other recipe on the site, please do leave a rating or comment and let us know how it went!
The Best S’mores Cake
Ingredients
For the sponge:
- 200 g dark chocolate
- 150 g unsalted butter, softened
- 90 g vegetable oil
- 300 g caster sugar
- 3 large eggs
- 40 g unsweetened dark cocoa powder
- 225 g self-raising flour
- 350 ml boiling water
- 10 g instant coffee granules
For the ganache
- 600 g dark chocolate
- 300 ml double cream
- Pinch of salt
For the biscuit crumb:
- 120 g lotus biscuits
- 40 g butter
For the marshmallow frosting:
- 300 g caster sugar
- 160 g egg whites
To decorate
- Marshmallows, as many as you like
Instructions
For the biscuit crumb:
- Blitz the lotus biscuits in a food processor (or bash in a sealed sandwich bag). Transfer to a bowl and mix in the melted butter.
To make the cake:
- Heat the oven to 170C fan/190c conventional/375f. Line 3 x 18cm cake tins with parchment.
- Melt the chocolate over a Bain Marie and leave to the side to cool.
- In a stand mixer, beat the softened butter and caster sugar together for 2 minutes until smooth and pale. Add the eggs, mixing in each one before adding the next.
- Then pour in the melted chocolate and mix briefly to combine. Drizzle in the oil while mixing.
- Add the flour, cocoa powder and pinch of salt. Mix well.
- In a jug, mix 350ml boiling water with the instant coffee granules. Pour slowly into the bowl of cake batter, mixing until the batter is smooth. It will look thin – that’s normal.
- Divide the mixture between the cake tins and bake for 25-30 minutes or until a skewer comes out clean when inserted.
To make the ganache:
- Finely chop the chocolate. Gently heat the double cream in a saucepan. Keep an eye on it as it can boil over easily.
- Add the chocolate to a large, heatproof bowl and once the cream is simmering, pour it over the chocolate. Add a pinch of salt and give it a minute to melt slightly before using a whisk to mix everything together until smooth.
- If you find the ganache has some small lumps of chocolate that won’t melt, you can gently heat over a Bain Marie whilst whisking to help things along. Set aside to cool or pop in the fridge to firm up slightly – don’t leave it too long as it can harden very quickly!
For the marshmallow frosting:
- Place sugar and egg whites into a heatproof bowl and place over a saucepan of barely simmering water.
- With a manual whisk, whisk until all the sugar is dissolved and you can no longer see or feel any small grains of sugar. To test this, rub a little of the mixture (it should be gently warm and not hot) between your forefinger and thumb. It should feel totally smooth. It will still look very loose; you aren’t whisking until thick.
- Once the sugar is dissolved, place this mixture into the bowl of a stand mixer and whisk until you get a thick and stiff meringue, about 10 minutes. If you don’t have a stand mixer, a handheld electric whisk will work.
- If you like, I find it easiest to transfer to a piping bag (or sandwich bag with the corner cut off). Otherwise, leave in the bowl and set aside until ready to assemble.
To assemble the cake:
- Place one sponge on a serving plate or cake stand.
- Spread a thick layer of ganache over the top. Top with biscuit crumbs and then pipe/spread on the marshmallow frosting. Top with the second sponge.
- Cover the entire cake with the remaining ganache, smoothing the sides with a palette knife or spatula. Then swipe on little patches of the marshmallow frosting and sprinkle crumbs around the base of the cake. Top with marshmallows, mine were homemade but shop-bought is of course fine.
- Use a blowtorch to lightly brown the marshmallow frosting and the marshmallows for a golden toasted s'mores look.
Notes
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
This s’mores cake is rich, dark and chocolatey, topped with marshmallow frosting, buttery cookie crumbs and chocolate ganache. It’s the perfect celebration cake.