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Mississippi Mud Brownies (Marshmallow Brownies)
5 from 292 votes

Mississippi Mud Brownies (Marshmallow Brownies)

Mississippi Mud Brownies feature rich chocolate brownies topped with a layer of puffed mini marshmallows and finished with a thick cocoa frosting. The brownies have a dense, fudgy texture complemented by the sticky marshmallow topping, giving a soft, gooey contrast. The frosting adds a smooth, creamy chocolate layer that balances the sweetness. This recipe involves baking, layering marshmallows briefly for puffing, then frosting once cooled for a classic texture and taste combination.

Prep Time
20 mins
Cook Time
25 mins
Total Time
45 mins
Servings: 24
Calories: 245 kcal
Course: Dessert
Cuisine: American

Ingredients

For the Brownies:
  • 1/3 cup cocoa powder unsweetened
  • 1/2 cup neutral cooking oil vegetable or canola oil, generic cooking oil
  • 1/2 cup butter , softened
  • 2 cups granulated sugar
  • 4 large egg
  • 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 cocoa powder unsweetened
  • 1/3 cup evaporated milk
  • 1 teaspoon vanilla extract
  • 3 - 3 1/2 cups powdered sugar

Instructions

    Cup of Yum
  1. Preheat oven to 350 degrees F. Grease a 9x13'' pan with non-stick cooking spray.
  2. In a large mixing bowl, pour oil over cocoa powder and mix.
  3. 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.
  4. Add flour and salt and stir to combine. 
  5. Pour batter into prepared pan. Bake for 25-30 minutes or until a toothpick inserted into the center comes out clean.
  6. 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.
  7. Once brownies are cool, make the frosting.
For the frosting:
  1. 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. 
  2. Add more powdered sugar, a cup at a time, mixing well, until you reach your desired frosting consistency. I usually use about 3 1/4 cups powdered sugar.
  3. 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

  • For clean slices, use a plastic knife to cut the frosted brownies to avoid sticking.
  • Mix in 1 cup nuts to the batter or add them with the marshmallows to create Rocky Road Brownies.
  • The brownies often taste better the day after baking as flavors settle, and they become easier to cut.
  • Frosting can be made up to two weeks in advance and stored airtight in the fridge.
  • Brownies freeze well, frosted or plain, for up to three months; thaw to room temperature before serving.

Nutrition Information

Calories 245kcal (12%) Carbohydrates 29g (10%) Protein 2g (4%) Fat 13g (20%) Saturated Fat 5g (25%) Cholesterol 52mg (17%) Sodium 185mg (8%) Potassium 67mg (1%) Fiber 1g (4%) Sugar 20g (40%) Vitamin A 290IU (6%) Vitamin C 0.1mg (0%) Calcium 20mg (2%) Iron 0.9mg (5%)

Nutrition Facts

Serving: 24 Serving

Amount Per Serving

Calories 245

% Daily Value*

Calories 245kcal 12%
Carbohydrates 29g 10%
Protein 2g 4%
Fat 13g 20%
Saturated Fat 5g 25%
Cholesterol 52mg 17%
Sodium 185mg 8%
Potassium 67mg 1%
Fiber 1g 4%
Sugar 20g 40%
Vitamin A 290IU 6%
Vitamin C 0.1mg 0%
Calcium 20mg 2%
Iron 0.9mg 5%

* Percent Daily Values are based on a 2,000 calorie diet.