Irresistible Mississippi Mud Brownies include an easy homemade brownie recipe topped with warm gooey marshmallows and chocolate frosting. 

A Mississippi Mud Brownie on a baking sheet with other cut brownies.

There are so many things to love about this Mississippi Mud Brownie recipe, which is why it’s a guaranteed crowd pleaser!  This recipe was inspired by my Mississippi Mud Cake recipe that has gone viral on facebook–it’s has nearly 30 MILLION views. Obviously you all love the chocolate/marshmallow combo as much as I do, so this brownie version is only appropriate.

How to make Mississippi Mud Brownies:

  • Make the brownie batter. Mix cocoa powder and oil. Add softened butter and mix until smooth. Add sugar and mix well. Add eggs, one at a time, mixing after each addition. Add vanilla. Stir in flour and salt, just until combined.
Three process photos for making brownie batter.
  • Bake. Pour batter into greased 9×13 inch pan and bake at 350 degrees F for 25-30 minutes or until a toothpick inserted into the center comes out clean.
  • Add Marshmallows. Remove brownies from the oven and sprinkle the marshmallows evenly on top. Return to the oven for 2-3 minutes or until the marshmallows are puffed. Remove from oven and allow them to cool completely. Once brownies are cool, make the frosting.
A pan of baked brownies, then marshmallows added on top.
  • Make the Frosting. Add melted butter, cocoa powdered, evaporated milk, vanilla, and 2 cups of powdered sugar to a mixing bowl and beat with electric beaters until smooth.  Add more powdered sugar, a cup at a time, mixing well, until you reach your desired frosting consistency. I usually use about 3 ¼ cups powdered sugar. Spread frosting over the cooled brownies.
A pan of brownies frosted with chocolate frosting.

Pro Tip for Cutting Frosted Brownies: Use a plastic knife! The frosting and marshmallows will cut smoother and easier, without making a sticky mess, if you use a plastic knife to cut the brownies. 

Make Ahead and Freezing Instructions:

To Make Ahead: I almost like these brownies even better the second day. Something about the way the flavors blend together and settle after several hours makes them even more irresistible. I also feel like they’re a little less “rich” on day two, and they are easier to cut. But, it may be hard to wait that long, so feel free to dig in right away. The frosting can be made up to 2 weeks in advance, stored in an airtight container in the fridge. 

To Freeze: The brownies can be frozen frosted or unfrosted, covered well, for up to 3 months. Allow to come to room temperature before serving. 

Don’t miss my Mississippi Mud Cake recipe, or other Brownie recipes like:

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Recipe

Mississippi Mud Brownies cut into squares.
Prep 20 mins
Cook 25 mins
Total 45 mins
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Ingredients
  

For the Brownies:

  • 1/3 cup unsweetened cocoa powder
  • 1/2 cup oil (vegetable or canola oil)
  • 1/2 cup butter , softened
  • 2 cups granulated sugar
  • 4 large eggs
  • 2 teaspoons vanilla extract
  • 1 1/2 cups all-purpose flour
  • 1 teaspoon salt
  • 3 cups mini marshmallows

For the Frosting:

  • 1/2 cup butter , melted
  • 1/3 cup unsweetened cocoa powder
  • 1/3 cup evaporated milk
  • 1 teaspoon vanilla extract
  • 3 – 3 1/2 cups powdered sugar

Instructions
 

  • Preheat oven to 350 degrees F. Grease a 9×13” pan with non-stick cooking spray.
  • In a large mixing bowl, pour oil over cocoa powder and mix.
    Oil and cocoa powder in a mixing bowl to make brownies.
  • Add softened butter and mix until smooth. Add sugar and mix for 1 minute. Add eggs, one at a time, mixing after each addition. Add vanilla and mix.
    Sugar, butter, oil creamed together.
  • Add flour and salt and stir to combine. 
    Flour and salt added to wet ingredients to make brownie batter.
  • Pour batter into prepared pan. Bake for 25-30 minutes or until a toothpick inserted into the center comes out clean.
    A pan of baked brownies.
  • Remove brownies from the oven and sprinkle the marshmallows evenly on top. Return to the oven for 2-3 minutes or until the marshmallows are puffed. Remove from oven and allow them to cool completely.
    A pan of baked brownies with marshmallows on top.
  • Once brownies are cool, make the frosting.

For the frosting:

  • Add melted butter, cocoa powdered, evaporated milk, vanilla, and 2 cups of powdered sugar to a mixing bowl and beat with electric beaters until smooth. 
    The ingredients for chocolate frosting, in a mixing bowl.
  • Add more powdered sugar, a cup at a time, mixing well, until you reach your desired frosting consistency. I usually use about 3 ¼ cups powdered sugar.
    A mixing bowl with homemade chocolate frosting.
  • Spread frosting over the cooled brownies and cut into squares. I’ve found a plastic knife works best to cut them, or if you make them 1 day in advance they are much easier to cut.

Notes

Tip for Cutting Frosted Brownies: Use a plastic knife! The frosting and marshmallows will cut smoother and easier, without making a sticky mess, if you use a plastic knife to cut the brownies. 
Rocky Road Brownies: Mix in 1 cup nuts to the brownie batter, or add nuts at the same time as the marshmallows.
Make Ahead Instructions: I almost like these brownies even better the second day. Something about the way the flavors blend together and settle after several hours makes them even more irresistible. I also feel like they’re a little less “rich” on day two, and they are easier to cut. But, it may be hard to wait that long, so feel free to dig in right away. The frosting can be made up to 2 weeks in advance, stored in an airtight container in the fridge. 
Freezing Instructions: The brownies can be frozen frosted or unfrosted, covered well, for up to 3 months. Allow to come to room temperature before serving. 

Nutrition

Calories: 245kcalCarbohydrates: 29gProtein: 2gFat: 13gSaturated Fat: 5gCholesterol: 52mgSodium: 185mgPotassium: 67mgFiber: 1gSugar: 20gVitamin A: 290IUVitamin C: 0.1mgCalcium: 20mgIron: 0.9mg

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I originally shared this recipe May 2017. Updated January 2021.

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About The Author

Lauren Allen

Welcome! I’m Lauren, a mom of four and lover of good food. Here you’ll find easy recipes and weeknight meal ideas made with real ingredients, with step-by-step photos and videos.

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Comments

  1. 5 stars
    Freeze them? Not at our house! Grandkids were waiting at the table as soon as the frosting was on! Good!

  2. 5 stars
    Great recipe. I made these for Fathers Day and I’m sure they will be gone before they hit the table. Thanks for sharing.

  3. 5 stars
    I made these for the grandkids and they loved them! They are very rich but absolutely delicious! And, they are very easy to make. Thank you for this recipe.

  4. I’ve been searching for this recipe for my southern husband. His mother died a few years back and she used to make a Mississippi mud pie. It sounds just like this , it was a brownie base with marshmallow fluff, except he said it had pecans. Would you just stir the pecans into the frosting?

  5. How far in advance can I make these? I am needing to serve 100 on Tuesday morning but won’t have time to make them over the weekend. Could I make them on Friday and serve them on Tuesday?

  6. The frosting was DELISH! Can I make the same basic recipe and instead of chocolate make say just vanilla or another flavor? Do I just omit the cocoa powder?

    1. Hi Jackie–omitting the cocoa wont work well. I’d suggest using my blondies recipes (blondies are “vanilla” brownies). Leave out the chocolate chips and use the same toppings as these mud brownies–https://tastesbetterfromscratch.com/triple-chip-blondies/.

  7. 3 stars
    My cake would not set. The edges were hard and the middle was soft. I’m a baker and never have this problem. Not sure what happened.

  8. 5 stars
    My whole family loved these. Definitely wait until the marshmallows/brownies are cooled before spreading the frosting. And use all the frosting! Perfect ratio of brownie/marshmallow/frosting. We will make these again!

  9. If I wait to cut and start eating them the day after it’s made so it’s not as rich, does it need to be refrigerated or can it stay out?

  10. 5 stars
    This is the second time I’ve made these. They are delicious. Everyone loves them. Unfortunately I was in such a hurry to make them this time that I put the frosting on while the marshmallows were still warm. Needless to say the toppings got all mixed together. They look a little odd but still delish!

  11. 5 stars
    my mom used to make these, since i was a teenager and everyone loved them. we lost track of the recipe so thanks for posting this. her legacy lives on

  12. If you make it the day before using cream instead of evaporated milk for the frosting, do you have to refrigerate? Does it still taste good after refrigeration?

  13. 4 stars
    Made these for Christmas & they were very good. I did cheat with a boxed brownie mix, so technically just used your topping recipe. Rich & chocolatey! Yum!

  14. I just made these and they look delicious, but it sank a little in the middle and has a raised crust around the edge. Can you tell me how to fix that?
    Thanks,
    Nancy

  15. 5 stars
    The icing is to die for!! I’ve used the evaporated milk as well as whipping cream, when I didn’t have the evaporated milk. Both are equally good. I’ve also forgotten to add the vanilla, and the icing was still FAB!! Also works great with your favorite boxed brownie mix! And I’m still rolling my eyes at the lady suggesting they are too sweet. Why make a dessert, much less a decadent brownie and then critique “it’s too sweet!”??? Isn’t that the point? Just use portion control and ENJOY!

  16. 4 stars
    My only critique is that these brownies are very sweet. I think they could do without the additional icing on top. But other than that, they’re delicious!

  17. These Mississippi Mud Brownie is worth the effort. The only critique I have to offer is to avoid over-baking. To other bakers out there, keep checking the brownie throughout the process in the oven. Also, I added caramel to the icing/glaze which adds extra flavor. I’m all about trying new ingredients, so I suggest adding a little chocolate with the marshmallows. This is worth the effort!

  18. What could be the reason for a few cracks on top of Mississipi mudcake The recipe cant be more fabouless Super!!!

  19. My brownies came out very cakey and dry. I must have over-baked them but the toothpick didn’t come out clean until after 30 minutes. The frosting is amazing!!!!

  20. Fahmazing!!! The frosting is out of this world! I just wanted a sweet treat one night and I saw these and decided that I had to try them. So easy and fast!

  21. 5 stars
    I made the Mississippi Mud Brownies and they were AMAZING. I also think they are better on the second day. Thank you so much. ~reese

  22. 5 stars
    I made these, I absolutely loved them. I truly think that they are better the second day. Thank you so much!!!

  23. Marshmallows made for an awkward sticky mix. It was like a they separated from the brownie. The frosting and the brownie it was amazing but I just wish now I would’ve left the marshmallows out or used fluff.

    1. Brittney, you probably let the marshmallows bake too long. That’s why they pulled away from the cake. You only let them bake until they start to puff a little bit then take them out of oven. Also you might not let them cool enough before you started to frost them. They have to be cooled throughly before you frost them. She has a photo above of the marshmallows just out of the oven and cooled. You can see from the photo how little the marshmallows rose before she took them out.

  24. 5 stars
    just making this fabolous cake. the browwnie mixture just came ok. also the marshmallows. now the frosting, while brownie cake is cooling down. but l think, the frosting will just come out as well as the brownie cake did.
    thank zou so much for the delicious recipe.

    renata

  25. 5 stars
    I loved how easy it was to make and how yummy it is. I cut it into squares by diping a butter knife in warm watter before each cut, it made it a lot easier to cut.

  26. 5 stars
    This is a great recipe. Right on queue for my style recipe. It turned out perfectly! Coworkers loved it. I will need to add choc chips to the brownie batter next time for a richer chocolate flavor. Or mini choc chips to the top of the marshmallows after it comes out of the oven for a sweeter treat! Great recipe!

  27. 5 stars
    I made this recipe tonight and the batter turned out perfectly. I had to add 10 minutes onto the cook time, but I think that was my oven. Delicious!

  28. 5 stars
    I’ve made Mississippi Mud Brownies for years, but have always added coconut and nuts to either/both the brownie and the frosting. I thought it simulated mud – with “rocks” and “grass” etc. 🙂

  29. My Mom made these when I was kid, but added the frosting right away to the hot marshmallows and swirled everything together. They were always a special treat with the marshmallow frosting!!

  30. I was really hopeful about this recipe. Mostly because I love brownies. The brownie layer and frosting were spot on. However, I thought the marshmallow later would be creamier but they were very stringing and chewy. It was very difficult to eat and my kids didn’t like it. I wonder if I cooked the marshmallows too long? Or is that how they are supposed to be? Would a jar of marshmallow fluff work?

    1. Hi Laura,
      That’s how they are supposed to be. Next time you could definitely use a jar of marshmallow fluff if you wan’t them to be creamier!

  31. 4 stars
    I made these and they were amazing, but I ended up having to removing most of the ganache and marshmallows; too sweet for my family’s taste. What I took off ended up being good to melt down and modify a bit for brownies my mom made that weren’t sweet enough, and planning to use the other half for homemade ice cream, adding pecans of course. Really wonderful overall though, even if it was a bit overbearing all together ❤️❤️

  32. 5 stars
    Excellent & easy. Making it now for the second time. Really a great recipe, that even a bachelor can do.

  33. Have you tried making these with coffee? If so, I’d love to know how to make that version. Definitely going to try this recipe out!

    1. I haven’t tried it, but you could try removing 1 -2 tablespoons of cocoa powder and adding espresso powder instead? Sounds yummy!

  34. If I make this a day in advance would you recommend putting it in the fridge?
    Thanks 🙂 I’m excited to try them!

  35. Hi Lauren,
    I would like to make this in a 8×8 pan , would I just half the recipe ? and change the bake time ?
    Thank you !
    They look delicious, can’t wait to make them.

    1. Hi Holly, yes you can just half the recipe and check it around 18 minutes or so, until a toothpick inserted into the brownies comes out clean. Enjoy!

  36. 5 stars
    Whenever we have a family gathering I get at least 10 texts from people wanting to know if I’m bringing these brownies. They are a family favorite and absolutely amazing.

  37. I used two boxes of brownie mix for the bottom. Tastes the same. Added chopped pecans in icing too. My favorite cake.

    1. Hi Tara,
      You can use either. Baking recipes usually mean unsalted butter (especially if you see salt added, like in this recipe). If you have salted butter you can just cut down on the salt in the recipe 🙂

  38. What is the difference between the cocoa in the brownie recipe and the unsweetened cocoa in the frosting recipe?

  39. 5 stars
    These were absolutely delicious! My husband, who is not crazy about chocolate brownies of any type, remarked about these being the best he’s ever had!
    Thank you. Will be making these often.

  40. 4 stars
    My brownies did not cook all the way through, so the entire inside was mush! 🙁 But the parts that were done, were AMAZING!!!

      1. Hmm. Where you using a metal or glass baking pan? You elevation and humidity could have also played a role. Next time try placing a piece of tinfoil over the brownies and cook them longer, until a toothpick inserted into the center comes out clean.

  41. Had the family over for dinner on Mother’s Day. I made this cake and pecan pie for dessert. The cake was so amazing that the pie was not even touched! Everyone loved the cake!
    I did not have enought cocoa powder so I used special dark for the cake, and the regular for the frosting. Even those who don’t care for dark chocolate loved it. This is a definite keeper. And I will continue to make the same way.
    Thanks for sharing this recipe.

    1. 4 stars
      one advice i would really recommend is to skip her homemade brownie mix and just bake a box brownie. After that then melt marshmallows and make frosting. it will make the recipe a little better. No shade at the lady who has made up this recipe because the idea and frosting is really good, but the box brownie is better for this recipe. Another note is that i only added 2 cups of powdered sugar and it was really sweet so if u have a sweet tooth then the 3 1/4 cup might work, but the 2 cups for me is best. Overall your idea is great.?

      1. I think the recipe is so good, are u saying to use a box because its easier for you cause this recipe is amazing