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These marshmallow brownies are total decadence! A thick layer of fudgy brownie, topped with gooey marshmallows, then topped with more fudgy brownies and chocolate chips! Easy to make and no mixer required!
I’m just going to say it - I am, in general, not the biggest marshmallow fan. I know - crazy right? Normally, I tend to find marshmallow desserts to be too sweet but holy smokes - these marshmallow swirl brownies are absolute perfection.
Brownies are one of my greatest loves. The base of these brownies is my one bowl brownies, which is one of my favorite recipes ever! The gooey marshmallow layer is baked onto the brownies, then sprinkled with more brownies pieces. To top it all off, we add mini chocolate chips to the warm marshmallow layer so they get soft and meltey!
Why These Marshmallow Swirl Brownies Are The Best
- These brownies have been tested both with regular dairy ingredients, and with dairy free ingredients! They can be made either way!
- You can easily customize this recipe - if you don’t want to add the brownie layer on top, I’ve provided instructions for making it without them.
- If you’re making these around the holiday season, I highly recommend sprinkling crushed candy canes on top, and if you’re making them in the summer, add some crushed up graham crackers over the marshmallow layer to make them into s'mores brownies!
- This recipe requires just a few key ingredients and you don’t even need a mixer!
- Cocoa Powder: I recommend unsweetened dutch processed cocoa powder works for these brownies, but you can use natural cocoa powder if that's what you have.
- Marshmallows: I tested these marshmallow swirl brownies with mini marshmallows and regular sized marshmallows, and mini marshmallows melt the best. Regular sized marshmallows will still work in a pinch. You can also use melted marshmallow fluff if you prefer!
- Flour: This recipe uses all purpose flour, and has not been tested with other types of flours.
- Butter: You can use regular dairy butter, or dairy free butter in this recipe!
Step By Step Instructions
STEP ONE: Prepare two pans: the first pan will be an 8x8 inch square baking pan. Line it with parchment paper, leaving some hanging over the sides to make it easier to remove the brownies later. Prepare a second pan, either a 9x5 or 8x4 loaf pan with parchment paper as well. Preheat the oven to 350°F.
STEP TWO: In a large microwave-safe bowl, melt the butter. Add in the brown sugar and white sugar and whisk until the mixture pulls away from the sides of the bowl as you whisk. Whisk in eggs and vanilla extract.
STEP THREE: Add in the flour, salt, and cocoa powder and whisk until combined (do not over mix). Add two thirds of the brownie batter into the prepared 8x8 pan, then add the remaining one third of the batter into the loaf pan. Bake both pans of brownies for 28-36 minutes, or until a toothpick inserted in the middle of each pan comes out with just a few wet crumbs on it.
STEP FOUR: When the brownies are ready, remove both pans from the oven, leaving the oven on. Set the loaf pan aside. Pour the mini marshmallows on top of the larger 8x8 pan of brownies, then place it back in the oven for 4-8 minutes, or until the marshmallows are gooey and the tops have started to turn golden brown. Meanwhile, use a spoon to break up the brownies in the loaf pan into chunks or small pieces.
STEP FIVE: Remove the brownies from the oven. Scoop out small chunks of brownie from the loaf pan and sprinkle over top of the marshmallow layer.
You can use your hands to do this if the brownies have cooled enough. Sprinkle all the crumbled up brownie over top of the marshmallows then sprinkle with more chocolate chips.
Fun Flavor Ideas!
There are a few super fun ways I like to make these marshmallow brownies even MORE extra than they already are, so I’m sharing a few below. Go big or go home right?!
- Peppermint Brownies: If you are making these brownies around Christmas and the holiday season, make them into candy cane marshmallow brownies! Add ½ teaspoon of peppermint extract to the brownie batter if desired, or just sprinkle crushed candy canes over the warm marshmallows!
- S’mores Brownies: If you’re a s’mores lover, sprinkle some chopped or crushed up graham crackers over the marshmallows along with the chocolate chips and crumbled up brownie chunks!
- Fluffernutter Brownies: Drizzle melted peanut butter over top of the melted marshmallows to make these into peanut butter marshmallow brownies!
FAQs and Expert Tips
Yes! If you’d rather use marshmallow fluff instead of mini marshmallows, heat 2 cups of marshmallow fluff for 15-20 seconds or until melted and pourable. Pour over top of the brownies, then sprinkle the crumbled brownies and chocolate chips over top.
In a pinch, they will work, but I highly recommend mini marshmallows. They melt easier and spread out more evenly than large marshmallows.
Yes you can! You do this two ways. You can make the brownie recipe as is, then bake it all in one pan. This will give you an extra thick brownie layer, and the brownies will take longer to bake. Alternatively, you can use this brownie recipe as the base layer.
Yes! To make the marshmallow layer even thicker you can add an extra half cup of mini marshmallows on top of the brownies.
- Don’t skip the parchment paper lining in the pans! It will be more difficult to remove the brownies from the pan to slice them if you skip this step.
- Properly measure your flour and cocoa powder - If you over-measure your flour or cocoa powder, the brownies won't be as fudgy and gooey! I strongly recommend weighing both ingredients with a kitchen scale or using the scoop and level method.
- Don't over-mix - The texture of brownies can be affected by over-mixing, so be careful to only whisk until the dry ingredients have been incorporated.
- Watch the bake time! Since you are baking two pans at once, you’ll want to be extra cautious of baking time. Over-baking your brownies will lead to tough brownies. Start checking on both pans early. The toothpick shouldn’t be completely clean when they come out, but shouldn’t be covered in batter. A few wet crumbs means they are done.
- Gently push the brownie pieces into the warm marshmallow layer to help them stay in place and create more of a layer of brownie on top.
- Resist the urge to slice the brownies while they’re warm. Because the brownies are super fudgy, and the marshmallows are hot and gooey, they need some time to set and firm up first.
Storage and Freezing Instructions
These brownies can be stored un-sliced in the baking pan covered tightly with tin foil, or sliced in an airtight container at room temperature for up to 5 days.
More Brownies and Bars You'll Love
If you make this recipe, let me know how it went in the comments below, I’d love to hear from you! You can also tag me on Instagram or Facebook so I can check it out!
Marshmallow Swirl Brownies
- 9x5 Loaf Pan
- 1 cup butter, melted (regular or dairy free)
- 1 cup granulated sugar
- 1 cup light brown sugar
- 1 tablespoon vanilla extract
- 3 eggs
- 1 cup all-purpose flour
- 1 cup unsweetened Dutch processed cocoa powder
- 1 teaspoon salt
- 3 tablespoon mini chocolate chips (regular or dairy free)
- 3½ cup mini marshmallows SEE NOTES
- Prepare two pans: the first pan will be an 8x8 inch square baking pan. Line it with parchment paper, leaving some hanging over the sides. This makes it easier to remove the brownies later. Prepare a second pan, either a 9x5 or 8x4 loaf pan. Line it with parchment paper. Preheat the oven to 350°F.(See notes if you'd like to make the brownies without the crumbled brownie layer on top)
- In a large microwave-safe bowl (or over the stove), melt the butter. Add in brown sugar and granulated sugar. Whisk until the mixture pulls away from the sides of the bowl as you whisk, like a paste.
- Whisk in the eggs and vanilla extract. Add flour, salt, and cocoa powder, then whisk until combined (do not over-mix!).
- Add two thirds of the brownie batter into the prepared 8x8 pan. Pour the remaining one third of the batter into the second pan (loaf pan). Bake both pans of brownies at the same time for 27-36 minute. To know when they're ready, insert a toothpick inserted in the middle of each pan - it should come out with a few wet crumbs on it when its ready (not covered in wet batter, but not completely clean).
- Remove the pans from the oven, but leave the oven on. Set the loaf pan aside. Pour mini marshmallows evenly on top of the brownies in the larger square baking pan and put them back in the oven for another 4-8 minutes, or until the marshmallows look gooey and have started to turn a light golden brown. Meanwhile, use a spoon to break up the brownies in the loaf pan into chunks or small pieces. Careful, they will still be hot!
- Remove the marshmallow brownies from the oven. Take small chunks of crumbled up brownie from the loaf pan and sprinkle over top of the marshmallow layer, gently pushing them into the marshmallows. Repeat with all the crumbled up brownie pieces, then evenly sprinkle with chocolate chips.
- Let cool before removing from the pan and slicing.
The calorie information provided for this recipe is an estimate. The accuracy of the calories listed is not guaranteed.
Gooey, chocolatey, and DELICIOUS. This is a keeper for my cookbook. Thanks for the recipe!
Hi Aly! So happy you loved them! Thanks so much for leaving a review 🙂
How much sugar can I reduced for less sweet brownies?
Hi, how much sugar can I reduce for not too sweet brownies?
Hi! I don't recommend reducing the sugar in this recipe, as it hasn't been tested that way. If you really want to, you can try reducing each type of sugar by a tablespoon.
Hi, could you please provide the metric measurements for the butter? We don't measure in cups in the UK and although you can buy cup measurements they are different to the US ones. Thank you
oops! That's been updated!
Loved the final turnout! Moist, indulgent and perfect for a Friday evening movie night with friends or a late night binge with ice cream or even with your Sunday morning coffee! The instructions are super clear and the tips are super useful. I baked my brownies for 32mins but will stick to the recipe's minimum time given (28mins) for the goey texture!
Hi Pallavi! I am so happy to hear that you loved the recipe - thank you so much for the review! 😀
If we make these using a commercial brownie mix, do we need two boxes of mix to fill the loaf pan and the 8x8?
Hi Greta, it will depend on your brownie mix. If the instructions on the brownie mix make anything larger than an 8x8 pan (like a 9x13), you will have enough batter to fill both pans. Enjoy!
Hi! Looking to give your recipe a try. I would love to make them in my 9x9, so I imagine they will be a bit thinner? But will they still be thick? I usually cut my brownies into 3x3 squares, hence the 9x9 pan. I am hoping they will still be a bit thick, and can you give me a best guess on time with a 9x9 pan? Thank you!
Hi Paula! They will be a bit thinner, but should still be overall fairly thick - the layer of marshmallows and extra brownies on top adds thickness to the overall brownie too. I would reduce the baking time by 5-10 minutes at first. It's hard to say since every oven is so different and the material of your baking pan will affect the baking time too (I always use an aluminium pan for brownies, which takes less time than a glass baking dish), so I always find it's better to just start checking on them early, around 17 minutes. I hope that helps!
these are my sons new favorite dessert! finished them off last weekend and he hasn't stopped asking for them since. sooo good. we used regular butter not dairy free and they were perfectly gooey. thanks for the recipe
Hi Micheal! Woohoo! I'm so glad that you both loved the brownies! Thanks for coming back to leave a review! 🙂
I know the flavour will change, but will this work with OIL instead of butter? If so, do I use 25% less?
Hi Monika, I haven't tried using oil instead of butter in this recipe, so I really can't say for sure how they'll turn out! I would try using the same amount, and the brownies may need to bake a little longer. Good luck!
Just whipped a batch of these and they are AMAZING! I love the marshmallow and brownie combo, so rich and fudgy.
Hi Kel! I am so happy that you loved them! Thanks so much for taking the time to come back and leave a review 🙂
Can u make them with the box brownie mix? I know it sounds tacky. Lol!
Hi Susan! No shame in boxed brownies 🙂 You could! You'd just have to check that whichever box mix you have will make enough brownies for the two pans if you plan to add the crumbled brownie layer on top!