Peanut butter marshmallow bars

Sometimes life calls for a ridiculously naughty treat, and this week my life was calling for such a treat. I felt like something chocolatey and I also felt like something with peanut butter so I smooshed two recipes together and was a happy girl.

We’re combining two of my favourite things – peanut butter marshmallow and afghans, aka the best biscuits in the world, and topping it off with a layer of fudgy chocolate icing. The base takes next to no time to prepare, and while it’s cooling you can whip up the marshmallow. The final product is on the sweet side so you’ll want to cut little slices.

Afghan base

300g butter, softened
130g sugar
255g flour
42g cocoa
85g cornflakes

Preheat your oven to 180°C and line a 9×13″ tin with baking paper. Use a deep-ish tin, like a roasting tin, so it’s deep enough for the layers.
Sift the flour and cocoa together into a bowl and set aside.
Cream butter and sugar until pale and fluffy, scrape down the bowl a couple of times.
Turn your mixer to low and slowly add the flour/cocoa mixture, followed by the cornflakes, then let everything mix together for 10 more seconds.
Tip the mixture into the baking tin and with wet hands, flatten it into an even layer.
Bake for 22 minutes. It should feel ‘set’ on top when you give it a gentle poke.
Cool completely on the tray before adding the marshmallow.
Peanut butter marshmallow

* you will need a candy thermometer.


4½ teaspoons powdered gelatin (I use McKenzie brand)
½c cold water
¾c sugar
½c liquid glucose, divided into 2
¼c water
pinch of salt
2 teaspoons vanilla extract
4-6 tablespoons creamy peanut butter (I used 6 for an extra peanut butter hit)


In a small microwave safe bowl, whisk together the gelatin and ½c water and let it soften for 10 minutes.
In a medium saucepan, add the sugar, ¼c of the glucose, ¼c of water and the pinch of salt. Stir together, add your candy thermometer and bring to the boil.

sugar syrup

Continue to boil, stirring occasionally, until the temperature reaches 240°F.
While the syrup is boiling, pour the other ¼c of glucose into the bowl of a stand mixer fitted with the whisk attachment. Microwave the gelatin for 30 seconds on high, stir, and then add to the mixer bowl. Set the speed to low and keep it running.
When the syrup reaches  240°F, slowly pour it into the mixer bowl.
Increase the speed to medium and beat for 5 minutes.
Increase the speed to medium high and beat for another 5 minutes.
Increase the speed to the highest setting and beat for 2-3 minutes.
Beat in vanilla.
Place the peanut butter in a small bowl and add one quarter of the marshmallow. Quickly stir it until it’s well blended. Scrape it back into the mixer bowl and gently fold it in to the remaining marshmallow. Fold until it’s mostly blended.


Tip the marshmallow onto the cooled afghan base and smooth it with a palette knife. Leave to set for 30 minutes before icing.

Chocolate icing
2½ cups icing sugar
2 teaspoons butter, melted (you don’t need to be too accurate here, butter is good!)
2 heaped dessert spoons of cocoa (see notes)
Splash of vanilla extract
Boiling water

Mix everything together until smooth, adding little splashes of water as necessary. I like to use a butter knife for this. If your icing is too runny, just add a little bit more icing sugar.

Pour the icing onto the set marshmallow and smooth with a palette knife. Leave to set for 30-40 minutes, then slice.

Store in an airtight tin for up to 5 days.


  • Marshmallow recipe via Shauna Sever.
  • I used double the amount of cocoa I normally use. This recipe needs a darker icing to offset the sweetness. Alternatively, you could use melted dark chocolate or ganache.

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