Easy Mississippi Mud Brownies Recipe (Marshmallow Brownies) have a soft brownie bottom, gooey marshmallows, and an irresistible chocolate frosting on top.

Most people love brownies, but Mississippi mud brownies or marshmallow brownies up the tastiness making them even more delectable. They are also incredibly easy to make. You can use your favorite boxed brownies or make homemade brownies. I have made so many different brownies over the years and these are the brownies which have become our favorite to have on repeat.
Try some of our other favorites, such as Frozen Peanut Butter Pie, Easy Lunch Lady Brownies, Lemon Brownies, Banana Split Cake, or Butterscotch Blondies.
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Ingredients for Marshmallow Brownies
Brownies
- brownie mix box, plus ingredients on the back of the box
- mini marshmallows
Chocolate frosting
- unsalted butter
- cocoa powder
- evaporated milk
- vanilla extract
- cups powdered sugar
FAQs
Mississippi Mud Brownies are rich, fudgy brownies topped with a layer of melted marshmallows, chocolate frosting, and sometimes nuts, creating a decadent and gooey dessert reminiscent of the classic Mississippi Mud Cake.
Yes, you can freeze Mississippi Mud Brownies. Wrap individual brownies tightly in plastic wrap, then place them in a freezer-safe bag or container. Freeze for up to 3 months. Thaw at room temperature before serving.
Yes, you can use large marshmallows if you don’t have mini marshmallows. Cut the large marshmallows into smaller pieces to distribute them evenly over the brownies.
Top Tips
- You will want to use fresh marshmallows so they will plump and melt correctly.
- The marshmallows will cut easier the next day. If you want to make these a day ahead or cut them the day after making, go for it.
- Cutting this type of brownie can be a sticky mess. There are a few tips I have tried that work. Use a plastic knife, spray a knife with cooking spray, or dip your knife in hot water before cutting.
- Store in an airtight container at room temperature or covered tightly with plastic wrap for 3-4 days or in the refrigerator 4-5 days.
- Variations: Frost the brownies and then place the marshmallows on top and brown with a kitchen torch.
- You can also add chocolate chips into the brownie mix, before baking.
How to make Mississippi Mud Brownies
- Preheat oven to 350 degrees. Prepare a 9 x 13-inch pan with nonstick spray. Combine brownie mix and bake, based on back of box directions, until a toothpick tested in the center comes out clean.
- Measure marshmallows and place on top of the hot brownies once they are baked.
- Place back into the oven for 2-3 minutes or until they start to puff. Remove from oven and cool completely.
- Once cooled, start making the frosting. In a large bowl, beat melted butter, cocoa, milk, and vanilla with 2 cups of powdered sugar.
- Pour in the rest of the powdered sugar mix until the frosting is ready. It will be light and fluffy, with no lumps.
- Spread the frosting over the marshmallow layer once they have cooled completely. It should smoothly spread.
- If you can let them set overnight, it will make cutting easier. Cut with a plastic knife, knife dipped into hot water, or a sharp knife sprayed with cooking spray. Then, enjoy!
Easy Mississippi Mud Brownies Recipe
Ingredients
Brownies
- 1 box brownies, plus ingredients on back of box
- 2 ½ cups mini marshmallows
Chocolate frosting
- ½ cups (1 stick) unsalted butter, melted
- ⅓ cup cocoa powder
- ⅓ cup evaporated milk
- 1 teaspoon vanilla extract
- 3 - 3 ½ cups powdered sugar
Instructions
Brownies
- Preheat oven to 350 degrees. Prepare a 9x13" baking dish with nonstick spray. Make and bake brownies, based on box directions or until a toothpick tested in the center comes out clean.
- Remove brownies from the oven and place marshmallows over the top.
- Place back into the oven for 2-3 minutes or until they start to puff. Remove from oven and cool completely.
Chocolate Frosting
- Once cooled, start making the frosting. In a large bowl, beat melted butter, cocoa, milk, and vanilla extract with 2 cups of powdered sugar.
- Pour in the rest of the powdered sugar, mix until the frosting is smooth. It will be light and fluffy, with no lumps.
- Spread the frosting over the marshmallows once they have completely cooled. It should smoothly spread.
- If you can let them set overnight, it will make them easier to cut. Cut with a plastic knife, knife dipped into hot water, or a knife sprayed with cooking spray. Enjoy!
Notes
- Variations: Frost the brownies and then place the marshmallows on top and brown with a kitchen torch.
- You can also add chocolate chips in with the brownie mix, before baking.
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