Peanut Butter Cornflake Marshmallow Treats

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These peanut butter cornflake marshmallow treats are squidy, nutty & packed full of flavour. They’re easy to make & you’ll only need 5 ingredients.

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peanut butter cornflake marshmallow treats

A nutty twist on a classic marshmallow treat!

To make these, we’re using toasted cornflakes instead of rice krispies for an extra crunchy, nutty flavour. That’s not all though! We’re also going to be blow torching the marshmallows, browning the butter & adding in a generous amount of peanut butter, for even more flavour.

These squidy cornflake marshmallow treats are sticky, crunchy, gooey & delicious! Plus, they’re incredibly easy prepare & make a fantastic lunchtime snack.

These peanut butter cornflake marshmallow treats are a twist on my brown butter biscoff rice krispie treats. We’re using the same techniques in this recipe but with some subtle adjustments, so that we can use cornflakes instead of rice krispies.

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Ingredient Notes

  • Cornflakes – Kellog’s cornflakes work best here. Make sure to use fresh cereal, for the crunchiest marshmallow treats.
  • Marshmallows – We’ll be toasting these, so it’s best to use regular or jumbo sized marshmallows.
  • Peanut Butter – I’d recommend using a good quality, smooth peanut butter for this recipe. I like to use Skippy but other brands will work as well.
  • Butter – Make sure to use unsalted butter, to avoid making the mix too salty. We’re browning this first, to find out more about this technique, take a look at our how to make brown butter guide.
  • Sea Salt – A light sprinkle of sea salt on top of the cornflake treats, enhances the flavour from the peanut butter & cuts through the sweetness of the marshmallows. A good sea salt works best here, I like to use Maldon.
toasted cornflakes
cornflake marshmallow treat stack

How To Make Peanut Butter Cornflake Marshmallow Treats

The full, printable recipe card for these cornflake treats can be found at the bottom of this post! Here’s a quick rundown of the recipe…

  1. Toast The Cornflakes
    First, we bake the cornflakes in the oven until they are well toasted. It’s important not to overcrowd your baking trays with cornflakes, so that they toast properly so you might need to toast the cereal in batches, depending on the size of your baking trays.
  2. Torch The Marshmallows
    Next, we place marshmallows onto a foil-lined baking tray then toast each one with a blowtorch (or under a grill/broiler if you haven’t got a blowtorch).
  3. Brown Butter
    Now we chop butter into evenly sized pieces, place into a large saucepan then cook over a medium heat until brown. This will only take 3-4 minutes & you’ll when the butter is done because it will smell nutty & the milk solids will have toasted & turned golden brown.
  4. Add Marshmallows & Peanut Butter
    Next, we take the pan of brown butter off the heat then immediately add in peanut butter & the toasted marshmallows. This then gets stirred (off the heat), until the marshmallows are just melted. This will only take a couple of minutes.
  5. Mix In Cornflakes
    Now we add the toasted cornflakes into the pan then stir, to coat each piece of cereal with marshmallow. It’s important to work quickly as soon as the cornflakes have been added in, as the mix will start to set as it begins to cool.
  6. Set In A Tin
    Finally, we tip the mix into a greased & lined tin then gently press down into an even layer, using the back of a spatula or a palette knife. A pinch of sea salt is sprinkled over the top then the cornflake treats are left to cool completely before being cut into portions.

Cornflake Marshmallow Treats Tips & Tricks

  • Toast The Cornflakes – For a deeper, caramelised flavour, toast the cornflakes in the oven first. This step doesn’t take long but adds a load of flavour!
  • Torch The Marshmallows – Using a blowtorch to toast the marshmallows before melting them, adds even more flavour. Think classic s’mores! If you haven’t got a blowtorch, use a grill/broiler instead.
  • Brown The Butter – Browning the butter gives these cornflake treats an extra nutty flavour that work’s great with the sweet marshmallows.
  • Get All Ingredients Ready Before Mixing – You’ll need to work quickly when mixing the cornflakes & marshmallows together, so it’s important to have all of your ingredients weighed out first.
  • Press The Mix Into The Tin Loosely – Pressing the cornflake mix loosely into the tin, keeps them soft & gooey. Press the mix in too hard & the treats will set too hard!
  • Serve At Room Temperature – These cornflake marshmallow treats are best stored at room temperature, in an airtight container.

Frequently Asked Questions

What marshmallows are best for cornflake treats?

As we’re going to be toasting them, it’s best to use regular or jumbo sized marshmallows. Avoid using mini marshmallows as these will be difficult to toast.

How do I keep cornflake marshmallow treats soft & gooey?

The best way to keep cornflake treats soft & gooey is to avoid getting the marshmallows too hot (the residual heat from the brown butter will melt them) & to loosely press the mix into the tin, to set.

How should cornflake marshmallow treats be stored?

Once set & portioned, cornflake marshmallow treats should be stored in an airtight container & are best eaten within 3 days.

How long do cornflake treats take to set?

Cornflake marshmallow treats will take at least an hour to set at room temperature. Make sure that they are completely cool before cutting them into portions.

How do I avoid getting soggy cornflakes when making cornflake treats?

To avoid soggy cornflakes when making marshmallow treats, you should use fresh cornflakes that have been toasted in the oven.

Can marshmallow cornflake treats be frozen?

I wouldn’t recommend freezing cornflake marshmallow treats as this could affect the texture. If you want to add a couple of extra days to the shelf life, they can be stored in the fridge instead of at room temperature.

Cooking Cornflake Treats In An Aga

With all of my recipes, I include cooking instructions for conventional ovens, fan ovens & also Agas. Here’s how to cook this recipe in an Aga…

Toast the cornflakes in the baking oven, on the bottom set of runners. If you need to toast them in batches, cook them one tray at a time. To brown the butter, use the boiling plate.

Equipment Used

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Peanut Butter Cornflake Marshmallow Treats

These peanut butter cornflake marshmallow treats are squidy, nutty & packed full of flavour. They're easy to make & you'll only need 5 ingredients.
Prep Time30 minutes
Total Time30 minutes
Course: Baking, Dessert, Snack
Cuisine: American
Servings: 12 Portions
Author: Ben Racey


  • 8" Square Baking Tin
  • Large Saucepan
  • Baking Trays
  • Blowtorch


  • 200 g Cornflakes
  • 400 g Marshmallows
  • 120 g Unsalted Butter
  • 150 g Smooth Peanut Butter
  • Sea Salt


  • Preheat an oven to 170°c/150°c fan (338°f/302°f).
  • Grease & line an 8" square baking tin with baking parchment. Lightly grease the parchment as well (with oil or butter). Set this aside for now.
  • Place the cornflakes onto a large baking tray then bake in the preheated oven for 6-8 minutes, until well toasted.
    Make sure not to overcrowd the baking tray with cornflakes. You may have to use two trays & cook the cereal in batches.
  • Line another baking tray with foil then place the marshmallows on top in a single layer, making sure that none of them are stuck together. Toast each marshmallow with a blowtorch, until well browned.
    If you haven't got a blowtorch, you can toast the marshmallows under a grill/broiler.
  • Next, chop the butter into evenly sized pieces then place into a large saucepan. Set over a medium heat & cook, stirring regularly until the butter is brown & smells nutty. This will take 3-4 minutes.
  • Take the pan of butter off the heat & immediately add in the peanut butter & toasted marshmallows. Stir with a rubber spatula, until the marshmallows are just melted (the residual heat from the butter will melt the marshmallows).
  • Stir the toasted cornflakes into the marshmallow mix, making sure that every piece of cereal is coated then tip into the prepared baking tin. Using a palette knife (or the back of a spatula), lightly press the mixture into the tin.
    Make sure not to press the mixture down too firmly, as this will cause it to set too hard.
  • Sprinkle a pinch of sea salt over the top of the cornflakes then leave to cool to room temperature (this will take at least an hour) before cutting into portions.


1. To Cook In An Aga – Toast the cornflakes in the baking oven, on the bottom set of runners. If you need to toast them in batches, cook them one tray at a time. To brown the butter, use the boiling plate.
2. Cornflakes – Kellogs’s cornflakes are best for these marshmallow treats. Make sure not to use stale cereal as they won’t be as crisp.
3. Marshmallows – Make sure not to use mini marshmallows as this will make toasting them difficult. Regular sized marshmallows are best but jumbo would work as well.
4. Peanut Butter – I’d recommend using a good quality, smooth peanut butter. I like Skippy peanut butter but other brands will work as well.
5. Storage – Once portioned, cornflake treats should be kept in an airtight container & are best eaten within 3 days.

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