This Mississippi mud cake is all about the layers with rich chocolate cake, gooey marshmallows, and a glossy fudgy frosting. Made in one easy 9×13 pan!
If you grew up with Mississippi mud cake, you know just how irresistible it is. That combination of soft chocolate cake, melty marshmallows, and rich frosting is pure comfort food, and the best part? It’s wonderfully easy to make. No stacking layers or fancy decorations. Just bake the cake, top it with marshmallows, and pour on the warm frosting for a nostalgic dessert that’s perfect for sharing. This one-pan wonder is just as welcome at potlucks as it is for weeknight cravings.
Why You’ll Love This Mississippi Mud Cake Recipe
- Three layers of deliciousness – Cake, marshmallow, and frosting in every bite.
- Easy to make – All in one 9×13 pan, no special tools required.
- Perfect for a crowd – Generous slices make it ideal for gatherings.
- Nostalgic flavor – A classic Southern favorite with timeless appeal.
Key Ingredients
See the recipe card below for ingredient quantities and full instructions.
- Unsalted butter – Creates a rich base for both the cake and frosting. Melted with cocoa for deep chocolate flavor.
- Unsweetened cocoa powder – Gives the cake and frosting their chocolatey depth. Use natural cocoa for classic flavor.
- Buttermilk – Adds tang and tenderness to the cake crumb.
- Mini marshmallows – The signature middle layer, puffing up into a gooey topping when added to the warm cake.
- Confectioners’ sugar – Sweetens and thickens the frosting so it drapes over the marshmallows without soaking in too much.
- Chopped nuts – Pecans or walnuts add a crunchy contrast. Feel free to add more if you like a nutty bite in every slice.
- Vanilla extract – Brings warmth and balance to the chocolate and marshmallow flavors.
How to Make Mississippi Mud Cake
Make the cake batter. In a medium saucepan, melt the butter with cocoa powder and water over medium heat. Bring just to a boil, then remove from heat and let cool for about 5 minutes. In a large mixing bowl, whisk together the sugar, flour, salt, and baking soda. Pour in the slightly cooled cocoa mixture and stir to combine. Add the eggs, buttermilk, and vanilla, mixing just until smooth.
Bake the cake. Spread the batter evenly in the prepared pan. Bake for 25 to 30 minutes, or until a toothpick inserted in the center comes out with just a few moist crumbs.
Add the marshmallows. As soon as the cake comes out of the oven, sprinkle the marshmallows evenly over the top. Return the cake to the oven for 2 to 3 minutes, just until the marshmallows puff and soften.
Make the frosting. In a medium saucepan, melt the butter with cocoa powder and milk. Remove from heat and whisk in the confectioners’ sugar, vanilla, and nuts (if using) until smooth.
Top the cake. While both the cake and frosting are still warm and the marshmallows are soft, pour the frosting evenly over the top to cover the marshmallow layer as thoroughly as possible. Don’t worry if you don’t cover it completely. Little bits of marshmallow peeking through are part of the charm.
Cool and serve. Let the cake cool completely so the layers set before slicing.
Tips for Success
- Cool slightly before adding eggs. Let the cocoa mixture rest for about 5 minutes after heating to avoid scrambling the eggs when mixing the batter.
- Mix just until combined. Over-mixing can make the cake dense. Stop as soon as the batter is smooth.
- Work quickly with the marshmallows. Sprinkle them over the cake right after it comes out of the oven so they start to melt into place.
- Don’t over-spread the frosting. Pour it evenly over the marshmallows while both are still warm and nudge gently to cover if necessary. It’s better to have some marshmallow peaks showing than to press into the layer.
- Adjust the nuts to taste. You’ll find a quantity range for the nuts in the frosting recipe. Use the amount to match the crunch you want.
Variations and Serving Ideas
- Add a flavor twist. Stir a pinch of espresso powder into the cake batter for deeper chocolate flavor, or swap the vanilla extract in the frosting for a splash of bourbon for a grown-up version.
- Switch up the nuts. Try toasted almonds, hazelnuts, or even a mix for extra flavor. Or skip them entirely for a nut-free cake.
- Change the marshmallows. Use large marshmallows cut into pieces or try flavored marshmallows for a playful twist.
- Serve it your way. Enjoy at room temperature for soft, gooey layers, or chill for a firmer texture. A scoop of vanilla ice cream or a dollop of whipped cream makes it extra indulgent.
- Make ahead. The cake keeps well for a day or two, making it a great choice for parties and potlucks.
How to Store
Room temperature: Cover the cake tightly and store at room temperature for up to 2 days.
Refrigerator: For longer storage, cover and refrigerate for up to 5 days. Let slices come to room temperature before serving for the best texture.
Freezer: Wrap individual slices or the whole cake tightly in plastic wrap, then in aluminum foil. Freeze for up to 2 months. Thaw overnight in the refrigerator or bring to room temperature before serving.
Bringing Back a Classic
Mississippi mud cake is proof that some desserts never go out of style. With its rich chocolate base, gooey marshmallow layer, and fudgy frosting, it’s a treat that’s as fun to make as it is to eat. Whether you’re sharing it at a potluck, bringing it to a family gathering, or making it “just because,” this one-pan wonder is sure to win over every chocolate lover at the table.
More Chocolate Cake Recipes
Mississippi Mud Cake
Ingredients
For the cake:
- 1 cup (226 g) unsalted butter
- 1/3 cup (28 g) unsweetened cocoa powder
- 1 cup (240 ml) water
- 2 cups (400 g) granulated sugar
- 2 cups (240 g) all-purpose flour
- 1/2 teaspoon salt
- 1 teaspoon baking soda
- 2 large eggs, at room temperature
- 1/2 cup (120 ml) buttermilk, at room temperature
- 1 teaspoon vanilla extract
For the topping and frosting:
- 3 to 4 cups mini marshmallows, enough to mostly cover the cake
- 1/2 cup (113 g) unsalted butter
- 1/4 cup (21 g) unsweetened cocoa powder
- 1/3 cup (80 ml) milk
- 3 to 3 1/2 cups (330 to 385 g) confectioners’ sugar, sifted
- 1 teaspoon vanilla extract
- 3/4 to 1 cup chopped pecans or walnuts, optional
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Instructions
To make the cake:
- Preheat oven to 350°F (175°C). Grease a 9×13-inch pan.
- In a medium saucepan, melt the butter with the cocoa powder and water over medium heat. Bring just to a boil, then remove from the heat. Let the cocoa mixture cool for about 5 minutes before adding to the dry ingredients. This helps prevent the eggs from cooking when added.
- In a large bowl, whisk together the sugar, flour, salt, and baking soda. Pour in the hot cocoa mixture and stir to combine.
- Add the eggs, buttermilk, and vanilla, stirring just until smooth.
- Pour the batter into the prepared pan and bake for 25–30 minutes, or until a toothpick comes out with a few moist crumbs.
To make the topping and frosting:
- As soon as the cake comes out of the oven, scatter the mini marshmallows evenly over the top. Return to the oven for 2–3 minutes, just until the marshmallows puff and soften. Cool briefly on a wire rack while you make the frosting.
- In a saucepan, melt the butter with the cocoa powder and milk. Remove from the heat and whisk in the confectioners’ sugar, vanilla, and nuts if using.
- While the frosting is still warm and the marshmallows are soft, pour or spoon the frosting evenly over the top of the warm cake. Gently spread as needed to cover, but don’t press or swirl. Try to keep the marshmallow layer intact.
- Let the cake cool completely before slicing. It cuts best once set.
Notes
- Let the cocoa mixture cool for about 5 minutes before adding to the dry ingredients to avoid scrambling the eggs.
- Pour the frosting over the marshmallows while both are still warm for the best texture and distinct layers. Don’t worry about completely covering every bit of marshmallow. It’s better to have a few puffy marshmallow peaks showing through than to overwork the top and lose that soft, gooey layer. I find that trying to cover as much of the cake while pouring works best because spreading it afterwards is a challenge.
- Store covered at room temperature for 2 days or in the refrigerator for up to 5 days. Freeze for up to 2 months.
