S'mores Brownies

These S'mores Brownies are next level. The gooiest, decadent chocolate brownies with a graham cracker crumb base and a thick layer of toasted homemade marshmallow frosting.

It doesn't get much more indulgent than ooey gooey s'mores in brownie form.  These decadent s'mores brownies have it all - the graham cracker base, the melty, fudgy brownies and the sweet marshmallow layer which has been torched to create that delicious toasted marshmallow flavor of s'mores.  

I've been having fun experimenting with developing fun brownie recipes lately, like my Red Velvet Brownies and my Tiramisu Brownies.  But one of my most popular recipe mash-ups are my S'mores Cupcakes, so I wanted to try to make a S'mores brownie recipe, and suffice it to say they were a resounding success!   If you're a s'mores lover, you're going to want to save this one! 

Ingredients

Though there are multiple different elements to this S'mores Brownie recipe, the ingredients list is actually fairly simple as a lot of the ingredients double up for different elements.

• Graham Crackers - Or digestive biscuits.
  
• Butter - Use unsalted butter - it doesn't need to be brought to room temperature as we will be melting it. 
  
• Eggs - The whole eggs are for the brownie batter, use large eggs and always free-range if you can.
  
• Egg Whites - For best results, use fresh eggs, separated, rather than carton egg whites. You can technically use carton egg whites but the meringue may not whip up as much so your marshmallow will be less fluffy and voluminous.  Don't throw away the egg yolks, see my egg yolk recipes for ideas on how to use them.
  
• Dark Chocolate - You definitely want to use dark chocolate here.  Even if you're not a dark chocolate fan, it will give the brownies a deep chocolate flavor and there will still be plenty of sweetness from the other ingredients.
  
  These brownies don't contain any cocoa powder, the chocolate flavor all comes from the chocolate, so make sure it's high-quality.  Also use real chocolate bars with at least 70% cocoa solids - not chocolate chips or candy bars. 
  
• Sugar - Use granulated sugar (caster sugar in the UK).
  
• Vanilla - Use vanilla extract or vanilla bean paste.  Bean paste will make some pretty speckles in your marshmallow. 
  
• Cream of Tartar - This will help keep the marshmallow frosting thick and stable.  If you can't find it, you can use lemon juice instead (twice as much lemon juice as cream of tartar), but your frosting may not be as stable without it.  

See the recipe card for quantities. 

What You'll Need

• 9-inch square pan
• Mixing bowl
• Whisk
• Stand mixer - with whisk attachment. This is for making the frosting. 
• Saucepan
• Heatproof Bowl
• Kitchen Torch

How To Make S'mores Brownies

There are three components to these incredible s'mores brownies:

1. Buttery biscuit base
2. Fudgy chocolate brownies
3. Marshmallow frosting

Make the Graham Cracker Crust

Using a graham cracker crumb crust for the base really gives these brownies that classic campfire s'mores flavor.

1. Preheat Your Oven to 350°F / 180°C (160° fan-assisted) and line a 9-inch square pan with parchment paper.
2. Put the graham cracker pieces or digestive biscuits in a food processor and blitz them until you have fine graham cracker crumbs.  If you don't have a food processor you can put them in a Ziploc bag instead and bash them up with a rolling pin.  

3. Melt the butter in the microwave in 30-second increments and then pour it into the crumbs.  You can pour the melted butter straight into the food processor, or mix into a bowl if you are using the bag method.  Mix until everything is well combined and it looks like wet sand.  
4. Tip the crumb mixture into the prepared pan and use your hands or a glass to flatten it out into a tightly packed, even layer.  Make sure you get into all the corners. Set aside.

Make the Chocolate Brownies

This is my ultimate fudgy brownie recipe and it's absolutely perfect for this s'mores brownies recipe because they are the most gooey and chocolatey brownies - just like the melty chocolate of s'mores.

1.  Chop up your chocolate up on a cutting board into small chunks.  Add the chocolate chunks to a microwave-safe bowl along with the butter and melt in 30-second increments, stirring in between, until the chocolate and butter have both melted. Set aside
2. In a large bowl, whisk together the eggs and sugar until thick and pale - kind of like custard.  There is no need for an electric mixer here, 30 seconds of vigorous whisking by hand should do it. 
3. Pour the melted chocolate mixture into the egg/sugar mixture, add the vanilla and mix together gently with the whisk until combined. 

4. Sift in the dry ingredients, including the flour and the salt, use a spoon or spatula to fold the flour in to the brownie batter until there are no more visible lumps of flour. It's okay if the batter has some lumps, as long as you can't see any white flour.  

5. Pour the brownie batter into the baking pan, on top of the graham cracker layer and let it spread out evenly.  
6. Bake for 25-30 minutes for soft, gooey brownies, or 30-35 minutes for more solid, dense brownies.  Personally, I think letting the brownies be slightly underbaked here makes them even more like s'mores.  
   
   When they are done, the top of the brownies will be dry and shiny, and when you test the middle of the brownies with a skewer, it will come out slightly chocolatey.  If it is caked in a thick layer of raw batter, the brownies need longer.  Baking time can vary depending on your oven, so look out for the physical signs they are ready.  

7. Let the brownies cool in the pan completely before attempting to remove them.  If you take them out too soon they will turn into a big sloppy mess all over your counter.  If they still seem too soft when trying to take them out, put them in the fridge for 20 minutes to firm up before taking them out of the pan. 

Make the Marshmallow Frosting

They wouldn't be s'mores brownies without marshmallow, so let's get to the fun part!  The marshmallow frosting is effectively a Swiss meringue. It might seem daunting but it's actually very easy to make. See my pavlova recipe for more expert tips on making meringue.

1. Make a double boiler by placing a heatproof bowl over a small saucepan with a few inches of water in it.  Do not let the bottom of the bowl touch the hot water.  Turn the heat on medium-low so the water is simmering.
2. In the bowl, whisk together the egg whites, sugar and cream of tartar.  Keep whisking constantly until the mixture is warm and the sugar has dissolved.  You don't have to whisk vigorously, just enough to keep it moving. You can test if it's ready by rubbing some of the mixture between your fingers - if you can feel any grains of sugar it needs longer.  
   
   If you would like to use a thermometer, you want the egg whites to reach a temperature of 160°F / 71°C.  

3. Once the egg whites are warm and the sugar has dissolved, whip the mixture on high speed, either with a stand mixer or an electric whisk.  (I just use the metal bowl from my stand mixer for the double boiler, then move it right over to the mixer without needing to transfer it to another bowl). 
4. Whip on high speed until stiff, glossy peaks form. Add the vanilla and whip for another 30 seconds - you should be able to make tall shapes with it when it is ready.  

How to Decorate S'mores Brownies

There are two methods to decorate your homemade s'mores brownies: 

Spread and Slice

• Spread the marshmallow frosting all over the brownie layer and use a spoon or spatula to make lots of shapes and texture on top - this will look super pretty when you toast it. 

• Use a kitchen torch to toast the marshmallow all over until it is golden brown.  I like mine quite dark and toasty as I am one of those freaks that likes to cremate my s'mores... but you can do yours however you like.

• Once toasted, use a sharp knife to cut your s'mores brownies into 9 or 16 squares.  These are quite rich and intense so I recommend the 16 squares.  

Slice and Pipe

Alternatively, you can slice your brownies first.  This is good if you want to pipe your marshmallow frosting on top for a more elegant finish. 

• Slice the brownies just as you would any regular brownies, into 9 or 16 slices.  

• Place the marshmallow frosting in a piping bag with your chosen decorating tip and pipe however you please. 

• Torch with the blow torch until golden brown.

Common Mistakes

Here are some common mistakes people make when baking this s'mores brownies recipe. 

• Overbaking the brownies - don't let the brownies bake for too long or they will come out dry and dense. A skewer should still come out slightly moist and chocolatey when they are done. 
  
• Trying to slice the brownies too soon - the s'mores brownies need to be completely cooled before you frost them or slice them, otherwise they will just make a big gooey mess.
  
• Getting egg yolk into the egg whites - If there is any trace of egg yolk, or any other fat in your egg whites, they will not whip up properly. Be very careful when separating your eggs. 
  
• Adding too much flour - these are nice fudgy brownies to make the s'mores effect - if you add too much flour they will be cakey instead.  Not measuring accurately can cause this, which is why I the best way to measure is with a kitchen scale rather than a measuring cup.  

Storage

Store your S'mores brownies in an airtight container at room temperature for up to 3 days.  Refrigerating the marshmallow frosting may make it become weepy. 

These are best when eaten on the same day as the marshmallow can lose some of its stability and fluffiness, depending on the humidity where you are.  

To make them last longer you can make the brownies ahead of time and make the marshmallow frosting on the day of serving.  The brownies alone will be good for up to 4 days. 

Watch How To Make Them

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More Brownie Recipes

For more gourmet brownie inspiration, try some of these: