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Easy Mississippi Mud Cake (with Box Cake)

Warm chocolate cake, sweet and gooey marshmallows, and homemade fudge icing poured over top… this Mississippi Mud Cake is a lesson in decadence! A classic dessert for all the chocolate lovers in your life. 

Make it a full Southern meal by serving up our Mississippi Pot Roast and Southern Cornbread before dessert!

Chocolate marshmallow cake with a bite taken out.

Chocolate Marshmallow Cake

This Mississippi Mud Cake is more than just a chocolate cake with marshmallows, it is THE chocolate cake with marshmallows!

Rich, moist, decadent, and indulgent – the chocolate lovers in your family will go nuts for this dessert.

Made easy by using a dressed up box of cake mix and marshmallows instead of marshmallow cream, this Mud Cake might be the best death by chocolate we could imagine!

Mississippi Mud Cake Ingredients:

Here’s a snippet of the main ingredients in this chocolatey cake. The full list of ingredients with instructions is further down the page.

  • Devil’s food cake mix – feel free to swap this out with your favorite chocolate or fudge flavored cake mix instead.
  • Large eggs.
  • Instant chocolate pudding mix – make sure to grab the instant pudding in the box and not the kind that needs to be cooked.
  • Sour cream – full fat sour cream is the best option. It keeps this cake nice and moist.
  • Oil – we like canola or vegetable oil. Feel free to use another neutral tasting oil if you prefer.
  • Coffee – brewed and cooled coffee works best. It enhances the chocolate flavor but doesn’t taste like coffee at all!
  • Mini marshmallows – these are super to sprinkle over the top. We prefer these to marshmallow creme, because they’re easier to use and don’t require spreading.
  • Unsalted butter – provides a silky, flavorful base for the fudge frosting.
  • Cocoa powder – unsweetened cocoa powder gives the frosting its signature chocolate flavor.
  • Powdered sugar – sweetens the frosting.
  • Heavy cream – gives the frosting richness and thins it out. Swap this out with half and half or milk if you prefer.

How to Make Mississippi Mud Cake

From scratch Fudge Frosting, fudgy chocolate cake, and a layer of marshmallows? Sign us up!

To make the mud cake:

  1. Preheat your oven to 350°F. Lightly grease a cake pan with cooking spray. Set aside.
  2. Use an electric mixer to combine the devil’s food cake mix, eggs, chocolate pudding mix, sour cream, water, oil, cooled coffee, and vanilla extract.
  3. Pour the cake batter into the prepared cake pan and bake for 30-40 minutes. A toothpick inserted in the center should come out clean when done.
Bowl of eggs, cake mix, sour cream, and oil.
Chocolate cake batter in a cake pan.
  1. Remove the cake from the oven, add the mini marshmallows in an even layer over the top, and bake for an additional 5-10 minutes until the marshmallows begin to puff up.
  2. Remove the cake once more and move onto the frosting while it cools.
Mini marshmallows on top of chocolate cake.

To make the fudge frosting:

  1. In a large mixing bowl, melt the butter and add the cocoa powder. Use an electric mixer to combine.
  2. Add in the vanilla extract, 2 cups of powdered sugar, and salt. Continue mixing until fully incorporated. Slowly add 2-3 tablespoons of heavy cream and mix again.
Cocoa powder and butter in a mixing bowl.
Chocolate frosting in a bowl.
  1. Repeat with the remaining sugar and cream until you reach your desired consistency. You may not use all of the heavy cream and that’s okay!
  2. Spread the frosting evenly over the marshmallows and enjoy!
Mississippi Mud Cake in a pan.

Tips For An Amazing Mississippi Mud Cake

  • Some versions add pecans to the mix for added crunch and flavor similar to a brownie. 
  • For even more sweetness, add a drizzle of caramel and sea salt over top.
  • This particular frosting is a spreadable frosting. It’s not like the cooked, thin, pourable icing that you see on many Mississippi mud cakes. For the pourable variety, check out our Coca Cola Cake recipe!
  • Make sure your cake pan is deep enough to hold the cake, marshmallows, and frosting. The cake bakes up tall and takes up a lot of space in most pans.

Storage

Storage: This Mississippi Mud Cake stores well in the refrigerator in an airtight container for up to 5 days. We don’t recommend leaving it out at room temperature because of the dairy used.

Freezing: Once baked, frosted, and completely cooled, the cake can be wrapped in plastic wrap and tin foil and frozen for up to 2 months. Thaw and serve.

Chocolate cake on a plate.

Why is it called a Mud Cake?

Weirdly enough, while this cake is mouth wateringly delicious, it got its name because of the chocolate color and icing texture resembling the mud on the banks of the Mississippi River. 

What’s the point of the sour cream in the cake mix?

Sour cream may feel like an odd addition but if you want a cake that’s incredibly moist and bakery quality, add sour cream. The fat content is higher than that of milk and will add a richness as well as moisture to your baked goods!

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Bite taken out of a Mississippi Mud Cake.

Easy Mississippi Mud Cake (with Box Cake)

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Prep Time: 20 minutes
Cook Time: 45 minutes
Total Time: 1 hour 5 minutes
Servings: 20 Servings

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Ingredients

For the Cake:

  • 15.25 ounces devil’s food cake mix 1 box
  • 3 large eggs
  • 3.4 ounces instant chocolate pudding 1 box
  • ¾ cup sour cream
  • ¾ cup canola oil or vegetable oil
  • ¼ cup water
  • ¼ cup coffee cooled
  • 1 tablespoon pure vanilla extract
  • 10 ounces mini marshmallows

For the Fudge Icing:

  • ½ cup unsalted butter melted
  • ½ cup cocoa powder
  • 1 teaspoon vanilla extract
  • ¼ teaspoon kosher salt
  • ⅓ to ½ cup heavy cream adjust to desired thickness
  • 4 cups powdered sugar

Instructions 

To Make the Cake:

  • Preheat the oven to 350°F, and lightly grease a 9×13-inch cake pan. Set aside.
  • Use an electric mixer to combine the cake mix, eggs, pudding mix, sour cream, oil, water, coffee, and vanilla. Mix until just combined.
    15.25 ounces devil’s food cake mix
    3 large eggs
    3.4 ounces instant chocolate pudding
    ¾ cup sour cream
    ¾ cup canola oil
    ¼ cup water
    ¼ cup coffee
    1 tablespoon pure vanilla extract
  • Transfer the batter to the prepared cake pan, and bake for 30 to 40 minutes or until a toothpick inserted in the center comes out clean.
  • Remove the cake from the oven and add the mini marshmallows in an even layer over the top. Return the cake to the oven for 5 to 10 minutes, just until the marshmallows begin to puff up and swell. Take the cake out of the oven a second time and make the frosting.
    10 ounces mini marshmallows

To Make the Fudge Frosting:

  • Melt the butter in a large mixing bowl. Then add the cocoa powder. Use an electric mixer to combine the butter and cocoa powder until well mixed.
    ½ cup unsalted butter
    ½ cup cocoa powder
  • Add the vanilla, 2 cups of powdered sugar, and salt. Continue mixing until the ingredients are incorporated then slowly add 2 to 3 tablespoons of heavy cream.
    1 teaspoon vanilla extract
    ¼ teaspoon kosher salt
  • Repeat with the remaining 2 cups of powdered sugar and 2 to 3 tablespoons of heavy cream or until the desired consistency is reached. You may not need all of the heavy cream.
  • Spread the frosting evenly over the marshmallows, and enjoy!
  • See post for tips, FAQs, and storage options.

Notes

*The calories listed are an approximation based on the ingredients in the recipe card and a serving size of 1 slice of cake. Actual calories will vary.
 
*For more information, tips, and answers to frequently asked questions, please refer to the post.

Nutrition

Serving: 1slice | Calories: 411kcal | Carbohydrates: 57g | Protein: 3g | Fat: 21g | Saturated Fat: 6g | Polyunsaturated Fat: 4g | Monounsaturated Fat: 9g | Trans Fat: 0.2g | Cholesterol: 46mg | Sodium: 338mg | Potassium: 144mg | Fiber: 2g | Sugar: 44g | Vitamin A: 290IU | Vitamin C: 0.1mg | Calcium: 53mg | Iron: 2mg
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