These Mississippi Mud Brownies are pure chocolate heaven. I love how they combine layers of rich brownie, gooey marshmallows, crunchy nuts, and a creamy chocolate frosting that melts right into every bite. Each square feels like a comforting dessert from a southern kitchen, full of texture and sweetness.
Why You’ll Love This Recipe
I adore this recipe because it’s incredibly easy to make yet tastes like a bakery-style treat. The boxed brownie mix saves time, while the marshmallows and cocoa frosting take things up a notch. I like how the nuts add a satisfying crunch and balance the sweetness perfectly. Whether it’s for a family gathering or a quiet evening dessert, these brownies never disappoint.
Ingredients
(Tip: You’ll find the full list of Ingredients and measurements in the recipe card below.)
1 box brownie mix (18.4 oz / 520 g)
1/4 cup water (60 ml)
1/2 cup vegetable oil (120 ml)
2 large eggs
1 cup powdered sugar (120 g)
1/4 cup cocoa powder (30 g)
1/4 cup milk (60 ml)
1/2 cup mini marshmallows (45 g)
1/2 cup chopped walnuts or pecans (60 g)
Directions
I preheat the oven to 350°F (175°C) and grease a 9×13 inch (23×33 cm) baking pan to keep the brownies from sticking.
In a large bowl, I mix together the brownie mix, water, vegetable oil, and eggs until smooth and glossy.
I pour half of the batter into the prepared pan and bake for about 20 minutes, just until the edges are set but the center remains slightly gooey.
While it bakes, I make the frosting by combining powdered sugar, cocoa powder, and milk until creamy.
Once the first layer is baked, I spread the frosting on top, then sprinkle the mini marshmallows and chopped nuts evenly.
I gently pour the remaining brownie batter over the toppings, spreading it to cover everything.
I bake again for another 25–30 minutes until the brownies are firm and a toothpick inserted in the center comes out with a few moist crumbs.
I sometimes swap the walnuts for pecans or even hazelnuts for a different nutty flavor.
To make it extra indulgent, I drizzle warm chocolate ganache over the top once it cools.
For a fun twist, I use peanut butter chips or caramel bits between the layers instead of marshmallows.
If I want a mocha kick, I add a teaspoon of instant coffee granules to the frosting.
Storage/Reheating
I store the brownies in an airtight container at room temperature for up to 3 days or in the refrigerator for up to a week. To reheat, I microwave a square for about 10–15 seconds to bring back that soft, gooey texture. These brownies also freeze well—just wrap each piece individually and store them for up to 2 months.
FAQs
How do I know when the brownies are done baking?
I check by inserting a toothpick into the center—it should come out with a few moist crumbs, not completely clean.
Can I use homemade brownie batter instead of boxed mix?
Yes, I often use my favorite homemade brownie recipe, and it works just as well.
What type of nuts work best in this recipe?
I usually prefer pecans for a southern touch, but walnuts or even almonds taste great too.
Can I make these brownies without marshmallows?
Absolutely. I sometimes skip the marshmallows and replace them with chocolate chips or shredded coconut.
How do I keep the brownies from drying out?
I always make sure to avoid overbaking and to store them in an airtight container once cooled.
Conclusion
I love making these Mississippi Mud Brownies whenever I crave something chocolatey and comforting. The mix of gooey marshmallows, creamy frosting, and dense brownies creates the perfect bite every time. They’re a timeless dessert that brings a little southern sweetness to any occasion.
