Marshmallow Brownies

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Rich, decadent chocolate brownies are topped off with gooey marshmallows and a fluffy chocolate frosting for the ultimate brownie.

A plate with a marshmallow brownie covered in chocolate frosting and a fork on the plate.

Who loves brownies?  I don’t know about you but brownies are a favorite in our house. Years ago I would make them from a box until a friend of mine gave me a cookbook and I tried the brownie recipe in it.  Who knew homemade brownies were so easy and so good?

Since then I’ll use a boxed brownie mix if I’m going to doctor it up but I like to make my own brownies if I’m just serving them with frosting or ganache on top.  However, I’ve found that people are just happy whenever brownies are around.

I have quite a few favorite brownie recipes.  These rich, chocolate Frosted Mocha Brownies are perfect for those with a sweet tooth. A tasty holiday brownie are these Red Velvet Swirl Brownies.  An old school copycat are these fun Cosmic Brownies.   For a classic I got with The Best Dark Chocolate Brownies.

In the case of these marshmallow brownies I went with a boxed brownie mix because I knew there was not only going to be homemade frosting on top but plenty of marshmallows as well so the actual brownie didn’t need to be homemade.

Pin Image: A plate with a chocolate frosted brownie on it, 2 forks, and a few mini marshmallows, text, a box of brownie mix and a bag of mini marshmallows.


  • Box of Brownie Mix
  • mini marshmallows
  • butter
  • powdered sugar
  • vanilla extract
  • cocoa powder (I used Rodelle)
  • milk

How to Make the Brownies:

  1. To Make the Brownies: Prepare the boxed brownie mix according to package directions. Add in the salt and vanilla extract if desired and mix well.  Pour into a greased 9 x 9 baking pan and bake for 30 minutes.
  2. To Add the Marshmallows: Remove the brownies from oven and sprinkle the mini marshmallows on top. Put the brownies back into the oven and bake for 3-5 minutes or until the marshmallows have puffed up. Remove from oven and let cool.
  3. To Make the Frosting: Combine all the ingredients for the frosting in a large bowl and beat with a mixer on medium speed until fluffy.  Spoon onto the brownies and spread with a spatula.

A pan of brownies with marshmallows on top.

I baked the brownie mix according to the package directions with the exception of adding in a tiny bit of salt and a bit of vanilla extract.   You don’t have to make these changes but I find that it gives the brownies a little better flavor.

Once you put the marshmallows on top and put them back into the oven keep an eye on them.  The marshmallows puff up and begin getting really big.   You don’t want them to get so big that they explode and drip all over your oven.

Can I make the brownies in a bigger pan?

You can make these brownies in a 9 x 13 baking dish instead of a 9 x 9 baking dish if you want thinner, chewier brownies.  If you do end up using a bigger pan you’ll need double the marshmallows and double the frosting recipe.  You’ll also want to pull the brownies out of the oven after 23-25 minutes instead of waiting for the full 30 minutes.

Can I use my favorite brownie recipe instead of using a box?

Absolutely!  While these brownies are already decadent and delicious feel free to use your favorite brownie recipe for the base of the brownies and cook according to the directions.  You can find some great homemade brownie recipes in this post.

A pan of brownies with chocolate frosting on top and a bag of cocoa powder in the background.

Can I use a can of frosting?

You can use a can of chocolate frosting if you don’t want to make your own.  I wouldn’t recommend it but I don’t like the taste of canned frosting.  Plus, since the brownies are from a box I feel like making your own frosting is a great way to make them taste homemade without making everything from scratch.

How do you get the brownies out of the pan?

I didn’t have too much trouble because I sprayed my pan with cooking spray before adding the brownie mix.  The marshmallows do get a little sticky on the edges though so you may want to run a butter knife around the edges before trying to cut and lift them out of the pan.

Another thing you can do is to line your pan with either foil or parchment paper.  Make sure to leave enough overhang to be able to grab it.  Then once the brownies have cooled and you’ve frosting them you can simply lift the entire batch out of the baking dish and cut.

A close up view of a hand holding a fork with chocolate frosting, marshmallows, and a brownie on it.

These brownies are amazing.  It’s like eating three layers of goodness!   First there’s the rich, chocolate fudge brownie layer.  I recommend getting a box of brownie mix that says fudge in the title.

Then there is the gooey marshmallow layer.   This makes these brownies taste almost like a s’mores bar.  It’s sticky, gooey, and totally tasty.

Finally you have the fluffy chocolate frosting.  The frosting is rich and sweet and brings the brownie together.  The entire thing is a chocolate lovers dream come true!

More Brownie Recipes:

These brownies can be covered and stored in the pan they were baked in for up to 4 days.   They can also be cut into squares and put into an air tight container and stored for up to 6 days.

A plate with a chocolate frosted brownie on it, 2 forks, and a few mini marshmallows.

If you’ve tried my Marshmallow Brownies or any other recipe on Hezzi-D’s Books and Cooks please take a minute to rate the recipe and leave a comment letting me know how you liked it. I love hearing from you! You can FOLLOW ME on:

A plate with a marshmallow brownie covered in chocolate frosting and a fork on the plate with a pan of the brownies in the background.

Marshmallow Brownies

Rich, decadent chocolate brownies topped off with gooey marshmallows and a fluffy chocolate frosting.
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Prep Time: 15 minutes
Cook Time: 30 minutes
Total Time: 45 minutes
Servings: 16 brownies
Author: Hezzi-D


For the brownies:

  • 1 box brownie mix 18 oz + ingredients to make the mix
  • 1 teaspoon vanilla extract
  • 1/2 teaspoon salt
  • 2 c. mini marshmallows

For the frosting:

  • 6 Tablespoons butter softened
  • 1 1/2 c. powdered sugar
  • 3 Tablespoons Dutch Process Cocoa Powder
  • 2 Tablespoons milk
  • 2 teaspoons vanilla


  • Preheat the oven to 350 degrees. Spray a 9 x 9 baking dish with cooking spray.
  • Prepare the brownie mix according to the package directions. Add vanilla and salt if desired.
  • Bake for 30 minutes.
  • Remove from oven and sprinkle with marshmallows so that they are in an even layer.
  • Return to the oven for 3-5 minutes or until the marshmallows puff up.
  • Remove from oven and cool completely.
  • To make the frosting place the butter in a large mixing bowl and beat with a mixer on medium high speed.
  • Add in the powdered sugar and cocoa powder and mix for 1-2 minutes or until totally incorporated.
  • Add the milk and vanilla and beat on high for 2 minutes or until fluffy.
  • Spread the frosting on top of the brownies in an even layer.
  • Cut into 16 squares and serve.


Recipe adapted from I Heart Naptime

A plate with a marshmallow brownie covered in chocolate frosting and a fork on the plate with a pan of the brownies in the background.

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