Mississippi Mud Cake with Cake Mix

This easy Mississippi mud cake starts with devil’s food cake mix and ends with a thick layer of mini marshmallows and rich fudge frosting. It’s soft, chocolatey, and just messy enough to live up to its name.

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Chocolate pudding mix, sour cream, and coffee dress up the cake mix without making the recipe different. Everything bakes in a 9×13-inch pan, so there’s plenty to share without stacking layers or decorating a thing.

It only takes about 20 minutes to prep and the rest is oven and cooling time.

This cake is rich, decadent, and so much fun to share! If you love chocolate and marshmallows, this one is for you.

An Easy Cake Mix Version

This isn’t a from-scratch Mississippi mud cake. The devil’s food cake mix and instant pudding make the base quick to prepare, while the sour cream helps keep it moist.

The brewed coffee deepens the chocolate flavor without making the cake taste like coffee. Just make sure it has cooled before adding it to the batter.

Mini marshmallows go over the cake during the last few minutes of baking. Once they puff up, a thick cocoa frosting is spread over the top. This frosting is rich and spreadable rather than the thin, pourable icing used on some Mississippi mud cakes.

If you love doctoring up a box of cake mix, try my earthquake cake, chocolate peanut butter bundt cake, or tres leches cake recipes next!

How to Make Mississippi Mud Cake

Combine the devil’s food cake mix, eggs, chocolate pudding mix, sour cream, oil, water, cooled coffee, and vanilla with an electric mixer. Mix just until everything is combined, then spread the batter evenly in a greased 9×13-inch pan.

Bake for 35 to 40 minutes and start checking the cake near the lower end of the baking time. It’s ready when a toothpick inserted into the center comes out clean.

Cover the warm cake with an even layer of mini marshmallows. Return it to the oven for another 5 to 10 minutes, just until the marshmallows begin to puff and swell. They don’t need to brown.

To make the fudge frosting, mix the melted butter and cocoa powder until smooth. Add the vanilla, salt, half of the powdered sugar, and a little of the heavy cream. Mix well, then repeat with the remaining powdered sugar, adding only as much cream as needed.

Spread the frosting over the puffed marshmallow layer. You can serve the cake warm and gooey or let it cool before cutting it into squares.

Getting Perfect Layers

Use a deep 9×13-inch cake pan. The cake rises quite a bit, and the marshmallows and frosting add even more height.

Add the heavy cream to the frosting gradually. It should be thick enough to stay in place but soft enough to spread without pulling the marshmallows away from the cake. You may not need the full amount of cream.

The marshmallows will be very soft while the cake is warm. For cleaner squares, let the finished cake cool before slicing. For a softer, gooier dessert, serve it while it’s still slightly warm.

Storing Mississippi Mud Cake

Cover the cooled cake tightly and store it in the refrigerator for up to 5 days. The frosting firms up when chilled, so let individual slices soften briefly at room temperature before serving.

Freezing isn’t recommended for the best texture because the marshmallow layer may change after thawing.

What to Serve with Mississippi Mud Cake

This cake is rich enough on its own, but adding a scoop of homemade vanilla ice cream is hard to beat. You can also add a spoonful of homemade whipped cream.

For drinks, try serving it with cinnamon coffee or a cold glass of homemade iced coffee. Both give you something simple to serve alongside the chocolate and marshmallow layers.

Easy Mississippi Mud Cake with Cake Mix

5 from 1 vote

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Author: Kimberly Vargo

Prep Time: 20 minutes minutes

Cook Time: 45 minutes minutes

Total Time: 1 hour hour 5 minutes 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 mix, 1 box
• ¾ cup sour cream
• ¾ cup canola oil, or vegetable oil
• ¼ cup water
• ¼ cup freshly brewed coffee, cooled to room temperature
• 1 tablespoon 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 salt
• 6 to 8 tablespoons heavy cream, adjust to desired thickness
• 4 cups powdered sugar

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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 mix

  ¾ cup sour cream

  ¾ cup canola oil

  ¼ cup water

  ¼ cup freshly brewed coffee

  1 tablespoon vanilla extract
• Transfer the batter to the prepared cake pan, and bake for 35 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 salt

  3 tablespoons heavy cream

  2 cups powdered sugar
• 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.
  3 tablespoons heavy cream

  2 cups powdered sugar
• Spread the frosting evenly over the marshmallows, and enjoy!

Notes

1. Use a deep 9×13-inch pan to leave room for the marshmallow and frosting layers.
2. Add the heavy cream gradually. You may not need the full amount.
3. Store the covered cake in the refrigerator for up to 5 days. Let slices soften briefly at room temperature before serving.
4. Freezing isn’t recommended for the best texture because the marshmallow layer may change after thawing.

Nutrition

Serving: 1sliceCalories: 411kcalCarbohydrates: 57gProtein: 3gFat: 21gSaturated Fat: 6gPolyunsaturated Fat: 4gMonounsaturated Fat: 9gTrans Fat: 0.2gCholesterol: 46mgSodium: 338mgPotassium: 144mgFiber: 2gSugar: 44gVitamin A: 290IUVitamin C: 0.1mgCalcium: 53mgIron: 2mg

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