
A decadently rich home-made chocolate brownies gets sandwiched between a crunchy biscuit layer and light as air layer of marshmallow fluff to bring you the ultimate S’mores Brownies.
S’mores Brownies with Marshmallow Fluff
What are S’mores Brownies I hear you saying, especially if you hark from the European side of the pond. And what on earth is marshmallow fluff.
Let’s take a step back first and break down what a s’mores is. Over here in the UK it’s not all that well known. Yes we’ll toast marshmallows over an open fire but we definitely don’t create s’mores out of it.
S’mores are a toasted marshmallow and a square of chocolate sandwiched between two graham crackers. The first published recipe was by the Girl Scouts in the US in 1927 and hear they document the toasting of the marshmallow in a campfire before constructing the s’mores. Head on over for more little known S’mores facts over on Real Simple.
I can well understand the lure of these sweet treats when going camping. They’re easy to transport, non perishable and delicious. You can imagine it can’t you … its cold, you’re huddled around the campfire and wanting a sweet treat after dinner. You grab a stick, shove a marshmallow on the end, toast it in the flames until its slightly charred and goey. Then you push it onto a crunchy graham cracker, top with a square of chocolate that will slowly melt once sandwiched together with another graham cracker. I mean yum! I get the appeal!
Onto S’mores Brownies
As a recipe developer, I sometimes want to take a standard recipe and transform it into a thing of decadence.
In a s’more the three main components are:
- Graham cracker,
- Marshmallow and
- Chocolate
When creating this recipe I needed to match that biscuit crunch along with rich chocolate and the signature toasted marshmallow.

The Biscuit Base
Here in the UK we don’t have graham crackers. But what we do have are digestive biscuits. Typically used as the biscuit base for cheesecakes, Digestives give the perfect crunch. The base is super easy to make. Whizz the biscuits in a food processor until fully crumbed, then add melted butter, a spoonful of sugar and a pinch of salt and whizz again. Then press firmly into the bottom of your baking pan and there you have it – one perfectly formed and delicious biscuit base.
Bonus points go to the fact that this base doesn’t need pre-baking. The brownie mix will go right onto and that’s when it gets baked.

The Brownie
Oh the brownie. Boy of boy do I love this brownies. It’s a recipe I use over and over again and doesn’t ever fail me.
There are four main steps to my recipe.
Step 1: Melt the butter, sugar and chocolate in a bain marie.
Step 2: In a bowl of a stand mixer, beat the eggs until pale and fluffy
Step 3: Add the chocolate mixture and the vanilla extract to the eggs and beat until thoroughly combined.
Step 4: Add the dry ingredients, flour, cocoa powder and salt and mix until combined
It’s as easy as that. Pour straight onto the biscuit base and bake for 20-25 minutes. The smell coming out of your kitchen at this point is heavenly!!
Once baked you then have to allow the biscuits base and brownie to cool thoroughly. I tend to leave it in the pan placed on a wire wrack to do this

Marshmallow Fluff
Finally, I hear you exclaim! Tell us more about marshmallow full. Alright. I’ll fill you in on the magic that is marshmallow fluff.
It originates in America. It’s basically a marshmallow spread, similar in taste to marshmallows but definitely not texture. It’s light and fluffy like meringue and can be torched just like marshmallow.
The main ingredients are:
- egg whites
- sugar
- cream of tartar
- salt
And how do you make Marshmallow Fluff
You’d think you’d be making a simple meringue. You kind of are but because you heat the eggs white with the sugar, melting and heating into an egg white sugar syrup (sounds great!), your on the path to making Swiss Meringue.
As soon as the sugar has dissolved you then have to add the cream of tartar and then whip that mixture until you have medium to stiff peaks. Add the salt (and vanilla if required, I didn’t in this recipe) and whip and your ready.
Unlike a French meringue or Italian meringue, because the egg whites have been heated the meringue mixture will be silky smooth, quite a bit denser and stickier then your standard meringue
And this is precisely what makes up a marshmallow fluff.
Use a piping bag and a tip of your choice to pipe really pretty swirls all over the top of your cooled brownie and biscuit base. (Alternatively pour over the brownie and smooth with the back of a spoon.
Now to add some colour- just like when toasting marshmallows on an open fire. Either use a blow torch and torch the meringue or if you dont have one (like I don’t) then place in the oven and grill (broil) for a couple of minutes. But keep an eagle eye on it as the sugar in the meringue does catch and toast super quickly.
You get to choose how toasty you like it. Either blackened and charred, or golden and toasty or lightly coloured (like me!). Bonus of making this at home.
NOTE: This isn’t for the faint hearted. It’s rich, decadent and not ‘good’ for you at all!!! But a little goes a long way. It’s a treat dessert not and everyday dessert (well I leave that decision to you!). But what I can tell you is, it’s divine and should definitely be tried if you’ve never tasted S’mores before. And even if you have, this is the most amazing take on a classic. We kept some for ourselves and gave the rest to the teachers at the girls’ school. They didn’t know what had hit them!
For more brownies and bars recipes try out these:
Chocolate Cherry Brownies. Recipe found here.
Browned Butter White Chocolate Blondies. Recipe found here.
Print
S’mores Brownies
- Prep Time: 45
- Cook Time: 25
- Total Time: 1 hour 10 minutes
- Yield: 16
- Category: Brownies
- Method: Baking
- Cuisine: American
Description
These decadent S’more brownies will soon be on your baking hit list. Crunchy biscuit base layered with rich chocolate brownies and topped with light marshmallow fluff come together for the ultimate brownie.
Ingredients
For the biscuit base
210g (16 biscuits) Digestive Biscuits
2 tablespoons granulated sugar
Pinch of fine sea salt
140g (3/4 cup and 2 tablespoons) unsalted butter, melted
For the brownies
200g (1 1/4 cups) dark chocolate, chopped
200g (1 cup and 1 tablespoon) butter, unsalted
200g (1 cup) caster sugar
3 eggs
1 tsp vanilla extract
125g (3/4 cups) plain flour
50g (1/2 cup) cocoa powder
1/2 tsp salt
For the marshmallow fluff
4 large egg whites
200g (1 cup) granulated sugar
¼ teaspoon cream of tartar
¼ teaspoon salt
1 teaspoon vanilla extract
Instructions
For the biscuit base
- Grease and line with greaseproof paper a square 9in x 9in brownie pan
- Add the biscuits, sugar, salt in a food processor and pulse until fine bread crumb consistency.
- Add the melted butter and pulse until combined and the crumbs start to clump.
- Pour crumb mix into the brownie tin and press down firmly until the base is level, smooth and compact. Set aside.
For the brownies
- Turn the oven on to 180C and line a 22cm square brownie tin with parchment paper (this will make it easier for you to remove the brownies once cooled)
- Using a bain-marie (Bowl sat snuggly over a saucepan of boiling water. Note: don’t let the water touch the bottom of the bowl). Place the butter, chopped chocolate and caster sugar into the bowl and stir until melted.
- Whisk together the dry ingredients: flour, cocoa powder and salt and set aside.
- In a medium bowl, with an electric beater or stand mixer, beat the eggs until pale and fluffy. Add the chocolate/butter/sugar mixture and vanilla extract and beat until combined.
- Then add the dry ingredients and mix until just combined.
- Pour into the prepared brownie tin onto of the biscuit base and smooth flat. Place in the oven and bake for 20-25 minutes. The edges should be firm but the centre should have a slight jiggle when shaken gently. Remove from the oven and place the tray on a wire rack and leave to cool completely. Use the baking paper to gently lift the brownie out of the tin.
For the marshmallow fluff
- Add the egg whites, sugar, cream of tartar and salt to a heat safe bowl of a stand mixer. Place the bowl over a saucepan filled with a couple of inches of simmering water.
- Heat the mixture, whisking constantly until the egg whites are warm to the touch and sugar has dissolved, about 3 – 4 minutes.
- Remove the bowl from the heat and transfer to your stand mixer fitted with the whisk attachment. Mix on high speed, until stiff, glossy peaks form, about 7-9 minutes. Add the vanilla during the last 10 seconds of mixing. Pipe onto the cooled brownies immediately.
- Using a blowtorch, torch the top of the meringue until browned. Or place under a grill for a few minutes to toast the marshmallow.
Notes
STORE: S’mores brownies can be stored in an airtight container at room temperature for up to 4 days.
Keywords: Brownies, S’mores, dessert

Hi there! I happened to see a post for Smores bars in a book. I wanted to try a more simpler version. While searching I came across your website and found your recipe that is easy to work with. I have a query. In the brownie process, do you let the melted chocolate to cool completely before adding it to the whipped eggs?
★★★★★
Hi Riya, Thanks so much for finding the steps uncomplicated. If you break them down into the three component of biscuit base, brownie and marshmallow fluff- its really quite simple. In response to your question- no need to cool the chocolate down. You’ll be beating the melted chocolate instantly into the whipped eggs and this will bring down the temperature of the chocolate straight away.
Thanks Riya,
Emma
This looks so yumm. I would add a littles less fluff. I want to store the leftover fluff. Can you suggest how to do it and how long will it last please ? Thanks
★★★★★
Hi Sana, Thanks, it is a mighty decadent but delicious dessert. I haven’t stored the fluff before so I can’t recommend if it would hold up – I’m inclined to think that it won’t last being stored. I would suggest scaling down the fluff component instead. xx
Hey, I’m hoping to make these over the weekend. Please can I ask the best way to slice with the marshmallow Topping? Looking to have very clean slices! Thank you!
Hi Hannah- I recommend heating your knife blade under hot water wiping it dry, rubbing with oil then slicing through the marshmallow. Wipe the blade clean, heat again and re-oil as needed. It takes time but you will get photo worthy slices!
What is a substitute for castor sugar. I have never heard of it or seen it in a store.
Hi Theresa, You can use normal granulated sugar. We find caster sugar here in the UK and the grains of sugar are just finer than granulated sugar. x
How long will these last stored at room temperature
Thank you
Lauren
Hi Lauren- they’ll keep in an airtight container for up to 4 days 🙂
I have made and they are AMAZING but the fluff has disintegrated and gone liquid like in places what have I done wrong?! Thanks
Hi Lauren, Hmmm there’s something not quite right with the meringue (which marshmallow fluff basically is). I am guessing that the meringue didn’t dry out whilst baking sufficiently. Therefor there was still too much moisture which when removed from the oven, seeped out. All ovens run differently so in your oven the bake time might need to be extended. Hope this helps xx