Mississippi Mud Cake

If you’re looking for the ultimate chocolate dessert, this Mississippi Mud Cake is it. Fudgy, gooey, and topped with a cloud of marshmallows and rich chocolate icing, it’s a true Southern classic that’s stood the test of time. This recipe starts with an easy to mix up chocolate sheet cake, then topped with mini marshmallows, and a quick chocolate icing poured over the top. The best part? No electric mixer is needed!

 

This cake is a dream for any chocolate lover. The base is rich and moist thanks to a blend of cocoa powder, hot coffee, and buttermilk. Then, while it’s still warm, it’s topped with melty mini marshmallows and finished with a glossy chocolate icing that seeps into every corner. 

Let’s just say my husband and I devoured this cake. Usually there is leftovers to gift to friends and family. Not this time. And you know what? No regrets. Every bite was enjoyed! 

​So what makes this cake truly special? It’s simple to prepare yet tastes like it came from a bakery. It’s rich and gooey, perfect for special occasions or just because. And the way the marshmallows and frosting meld together into a fudgy layer is nothing short of magical. Honestly, once you make this cake, you’ll understand why so many people call it the best Mississippi Mud Cake they’ve ever had.

If you’re new to Mississippi mud cake..let me give you a quick lesson. It was supposedly named after representing the muddy banks of the Mississippi River. The name may come from the muddy banks of the Mississippi River, but one bite and you’ll realize there’s nothing messy about how decadent this cake really is.

Ingredient Notes

For a full list of ingredients and amount refer to the recipe card at the bottom of the post. Here a few things to mention on some of the ingredients:

• Cocoa Powder – Use unsweetened natural cocoa powder for that classic flavor. I like to use Dutch process cocoa powder as it’s got a richer chocolate taste.
• Eggs – Make sure they’re at room temperature so they incorporate smoothly into the batter. Place in a bowl of warm water for 10 minutes. Here is my full tutorial on how to bring eggs to room temperature quickly.
• Flour – Regular all-purpose flour works best. If you need it gluten-free, use a good 1:1 baking blend. I like King Arthur Flour’s 1:1 gluten free flour.
• Mini Marshmallows – The star topping! If you don’t have minis, you can cut larger marshmallows into smaller pieces.
• Buttermilk – If you don’t have any buttermilk don’t fret! You can always make a quick homemade version by combining milk with vinegar or lemon juice. Here is my complete tutorial on how to make homemade buttermilk. 
• Oil – I like to use a neutral-tasting oil such as vegetable or canola oil. Oil is what keeps this cake super moist. I recommend this over using melted butter.
• Hot coffee – This helps to enhance the chocolate flavor. If you don’t have any, then use boiling water with instant espresso powder added to it. Or just use hot water!

How to Make Mississippi Mud Cake

1. Prep your pan and oven.
Position a rack in the center of your oven and preheat to 350°F (180^oC). Grease a 9×13-inch cake pan with nonstick cooking spray. You can also line the pan with parchment paper for easy release.

2. Mix the dry ingredients.
In a large mixing bowl, whisk together the sugar, flour, cocoa, baking powder, baking soda, and salt. Sifting helps prevent lumps in the batter and ensures a smooth, tender crumb.

I always recommend weighing your flour with a scale for accuracy and so you don’t end up with a dry, dense cake. If you’re using a measuring cup then spoon the flour into your cup and level it off for the best accuracy.

3. Mix the wet ingredients.
In a second bowl, whisk together the eggs, buttermilk, vegetable oil, and vanilla until well combined.

Here is a pro baking tip for you: Make sure your eggs and buttermilk are at room temperature — this helps them blend more easily into the batter.

4. Combine the batters.
Add the wet ingredients to the dry mixture. Using a rubber spatula, stir gently until no streaks of flour remain.

Be careful not to overmix; overmixing can create a dense cake. I always like to stop mixing once the last of the flour has been mixed in.

5. Add the hot coffee.
Pour in the hot coffee and stir until smooth. The batter will be thin — that’s exactly what you want. 

6. Bake the cake.
Pour the batter into the prepared pan and bake for 40–45 minutes, or until a wooden pick inserted in the center comes out with a few moist crumbs. Don’t wait until the toothpick is completely clean or that means it’s overbaked. You want a toothpick with no wet batter and the top to spring back when touched.

Avoid overbaking — a slightly fudgy center is what makes this cake so irresistible. Let the cake rest for about 5 minutes.

7. Top with marshmallows.
While the cake is still warm, sprinkle the entire bag of mini marshmallows evenly over the top. Return to the oven for 3–5 minutes, just until the marshmallows are puffed and slightly melted. Don’t let them brown — you want soft, gooey marshmallows.

Then remove the pan and make the icing!

8. Make the icing.

This icing couldn’t be simpler! It’s made on the stovetop in just a few minutes.

In a small saucepan over medium heat, melt the butter. Stir in the cocoa powder and salt, whisking until smooth. Remove from heat, then stir in vanilla.

Gradually whisk in the powdered sugar and milk until the icing is smooth and pourable. If it feels too thick, add an extra splash of milk.

9. Finish the cake.
Pour the warm icing directly over the marshmallow layer, gently spreading it with an offset spatula to cover the top of the cake in an even layer. The icing will seep down into the marshmallows and create that signature fudgy topping.

10. Cool, slice, and serve.
Let the cake cool completely before slicing for clean pieces — though no one will complain if you cut into it while it’s still gooey. Serve as-is, or for an extra touch, serve with a dollop of homemade whipped cream!

This Mississippi Mud Cake is rich, gooey, and downright indulgent — the kind of dessert that makes people close their eyes and say “oh wow” with the first bite. Whether you’re baking for a potluck, a holiday table, or just a family chocolate craving, this cake is guaranteed to be a hit.