These fluffernutter brownies are a the ultimate peanut butter and marshmallow brownie bar! Super decadent and fudgy chocolate brownies with peanut butter chips, topped with a sticky marshmallow fluff and peanut butter swirl.
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Why you'll love these
- Super indulgent and gooey - fudgy brownies topped in a sticky sweet swirl of peanut butter and marshmallow.
- Loaded with peanut butter chips - not only do these gooey brownies have peanut butter in the swirl, but they're loaded with added peanut butter chips for an extra punch of sweet nutty perfection!
- Easy one bowl recipe - no need to mess around with loads of equipment for these incredible brownies! All you'll need to make the thick brownie batter is one mixing bowl, a whisk, spatula and sieve.
- Stays fresh and fudgy for days - these fluffernutter brownies stay super gooey, fresh and flavorful for about 4 days, easily. Not that you'll have leftovers hanging around for long!
What is a Fluffernutter?
A classic fluffernutter is a marshmallow and peanut butter sandwich. Originally a New England specialty, the sticky sweet and nutty combination of peanut butter with marshmallow fluff has become a popular duo, which you can find enjoyed all over!
These brownies take the flavours of the fluffernutter and turn them into the ultimate dessert bar. Rich and fudgy brownies packed with peanut butter chips and topped in a swirl of sticky marshmallow fluff and peanut butter.
Ingredient Notes
To make these fudgy peanut butter chip brownies topped with marshmallows and more peanut butter, you'll need:
- Eggs - these should be large eggs, ideally at room temperature for baking. Room temperature eggs beat more evenly into doughs and batters and will cook more evenly than an egg straight from the fridge. This isn't to say that I've not made brownies with chilled eggs before - they do still work, so don't stress if you've not let your eggs warm up first!
- Oil - a flavorless oil like sunflower or canola oil works best here. You can use olive oil, but olive oil is a very strong flavor which will leave a taste in your brownies.
- Water - just a few tablespoons of tap water to get your batter to the perfect consistency!
- Vanilla extract
- Flour - either all purpose flour or plain flour work here.
- Cocoa powder - a good quality dutch processed cocoa powder works best.
- Salt
- Peanut butter chips - to add little notes of extra peanut butter in these fluffernutter brownies, I've added peanut butter chips straight to the batter. If you can't find these in your local store, you can also add chocolate chips to give you a little something extra or leave this out.
- Peanut butter - I like to use crunchy peanut butter in this recipe, to add to the flavour and texture. You can use smooth peanut butter instead.
- Marshmallow fluff - key to a fluffernutter! You'll want a good amount of sticky marshmallow cream for the swirl on these brownies.
How to Make a Fudgy Fluffernutter Brownie
This is a fairly straightforward one bowl recipe!
To start, you'll want to line your baking pan with parchment paper and preheat your oven. Then get cracking with the batter.
- Begin by whisking together the eggs, oil, water and vanilla in a large mixing bowl. This should be whisked for a minute or two until it is well emulsified.
- Then, sift the flour, cocoa powder, sugar, powdered sugar and salt straight into the wet ingredients.
- Using a spatula stir the batter until it is just combined into a thick brownie dough. (image 1 below)
- Add the peanut butter chips and stir to distribute.
- Now, pour the batter into your lined pan and spread it evenly into the edges and corners. (image 2 below)
- Dollop the peanut butter across the top of the batter and then dollop the marshmallow fluff.
- Using a kitchen knife, swirl the peanut butter and fluff with the brownie batter. Be sure that you work the batter as evenly as possible and end your swirling with the batter still distributed into the corners and edges of the baking tray. (images 3 and 4 below)
- Place in the centre of your preheated oven and bake for about 30-40 minutes until a toothpick inserted in the middle comes out mostly clean.
- Remove from the oven and allow to cool in the pan for about 2 hours before slicing.
Expert Baking Tips
My top tips for this recipe are:
- Lining your baking tray isn't 100% essential - you can successfully bake these brownies without the lining. But, since they are super rich and gooey, it is a lot easier to get them out of the pan neatly if you line it first!
- The batter should be pretty thick and will move around as you swirl in the toppings. To make things a little easier, hold the knife at a slight angle. This helps to reduce the tension and will let you swirl the peanut butter and fluff through the brownie batter.
- It's hard to decide when to stop swirling! Once you've got a nice mingling of the toppings with the brownie batter, it's probably time to be done. Just be sure that your batter is still spread into the edges and corners of the baking tray and that it hasn't become super uneven in the pan. One side shouldn't be deeper/more full than the other!
- When baking fudgy brownies, you want the toothpick to come out mostly, but not entirely, clean. This will mean that the inside of the brownie will be super gooey!
- Since these are super gooey, it's important to let them cool down before slicing them. This will make it easier to cut them into orderly pieces. Of course, if you can't wait, you can dig in as soon as you like, but this is fair warning that it will be messy!!
Variations
There are always so many ways to play around with a recipe! This one is no different. Some of my favorite alternative options are:
- Smooth versus crunchy peanut butter - a quick and easy variation here is to opt for a different style of peanut butter. Personally I use and recommend a thick crunchy peanut butter, because this will pack flavour and a bit of texture into the bake. You can absolutely use smooth peanut butter here.
- Different nut butters - a fluffernutter is peanut butter and marshmallow fluff, but that doesn't mean you have to be restricted to some sort of 'authentic' flavour combo here. If you like almond butter or a pecan butter, but go great with marshmallow fluff and with chocolate. Give them a try here! Do be aware that different nut butters (even different brands of peanut butter) may swirl in a bit different since they'll have different consistencies.
- Chocolate chips - if you want to add even more chocolate decadence into these brownies, an easy way to get your fix will be chocolate chips. Simply substitute half (or all) of the peanut butter chips with some chocolate chips. These can be dark, milk or white chocolate chips or solid chocolate chopped into small chunks. Avoid large chunks or the batter will become more difficult to spread and swirl.
- Adding nuts - you can opt to add nuts to these brownies in the same way as the chocolate chips. Chopped peanuts - salted or unsalted - go great in these brownies. Be aware that salted peanuts will dramatically increase the overall saltiness of the brownies.
- Sprinkles - I know there are sprinkle fans out there who will be looking at this bake and wondering if they can add sprinkles? Yes, absolutely! I'd recommend adding any colourful sprinkles towards the end of the swirling - this will allow for good distribution over the top and preserving colour!
Storage Tips
Once your fluffernutter brownies have been cooled down and sliced, they can either be served immediately or stored for later. For best results, store in an airtight container at room temperature.
A couple of quick storage tips:
- Avoid having a storage bag or plastic wrap placed directly on top of these as the marshmallow fluff is prone to sticking.
- It's best to slice before storing - this gives you options for different storage containers or to freeze some if you want to have a sneaky stash of these ready for weeks or months in the future.
- Don't stack - just like the issue with having the storage container touching the top, stacking will cause sticking as these are both super gooey and sticky with marshmallow!
FAQs
These peanut butter and marshmallow brownies will keep for several days! They stay surprisingly fresh and fudgy for about 4 days and may last longer (though I've never managed to keep them around much beyond 4 days!).
Store them in an airtight container at room temperature for best results.
Yes! These fluffernutter brownies freeze really well. Follow the recipe as directed and allow to cool completely. For freezing, I recommend cutting first, then you can pack in freezer bags or containers, which means you can defrost one or a few at a time, rather than the whole tray.
These will keep for about 3 months in the freezer. Allow to defrost at room temperature before serving.
Peanut butter chips are usually available in my grocery store or online through Amazon. But, if you're not able to find these in your area, don't worry! You can simply leave these out, or substitute with chocolate chips or peanuts. The process won't change, nor will the cooking times be impacted.
Oh no! This can happen, especially when going for super fudgy brownies.
It may be that you've not left your fluffernutter brownies long enough to cool - either try waiting a little longer or you can place the pan in the fridge for them to cool more quickly.
It may also happen if you've not baked the brownies long enough. The toothpick should be mostly clean when inserted in the centre - that means flecks of brownie on it. It should not still be a liquid batter in the centre - if it is leave the brownies to cook a bit longer.
Looking for more sticky sweet marshmallowy treats? Try:
- Chocolate Chip and Marshmallow Cookies
- Chocolate Marshmallow Brownies
- S'mores Cinnamon Rolls
- Chai Marshmallows
- Pumpkin Spice Marshmallows
- S'mores Blondies
Fluffernutter Brownies
Ingredients
- 3 large eggs ideally at room temperature
- ¾ cup flavorless oil such as sunflower oil or canola oil
- 3 tablespoon water tap water should be fine
- 1 teaspoon vanilla extract
- 1 cup all purpose flour or plain flour
- 1 cup cocoa powder
- ¾ cup granulated sugar or caster sugar
- ¾ cup powdered sugar or icing sugar
- 1 teaspoon salt
- 6 oz peanut butter chips
- ½ cup peanut butter smooth or crunchy
- 1 cup marshmallow fluff about ⅔ of a standard size jar
Instructions
- Begin by lining an 8" square baking pan with parchment paper and preheating your oven to 350°F (175C/155C Fan).
- In a large mixing bowl, whisk together the eggs, oil, water and vanilla until fully emulsified (about 2 minutes).
- Sift the flour, cocoa powder, sugar, powdered sugar and salt into the wet ingredients, then stir with a spatula until just combined into a thick batter.
- Add the peanut butter chips and stir to distribute.
- Pour the batter into the lined pan and spread into an even layer.
- Add dollops of your peanut butter over the top of the batter, then add dollops of the marshmallow fluff.
- Using a kitchen knife, swirl these into your batter (see note).
- Place the tray in the centre of your preheated oven to bake for about 30-40 minutes, until a toothpick inserted in the middle comes out mostly (but not entirely) clean.
- Remove from the oven and allow to cool in the pan for about 2 hours before slicing.
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