Moist chocolate cake topped with marshmallows, pecans, and warm chocolate frosting, this Mississippi mud cake is made to look like the mud and rocks of the Mississippi River!
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Old-Fashioned Mississippi Mud Cake
This Mississippi mud cake is for anyone who loves rich chocolate desserts and quick, one-bowl recipes. I have a refreshing mud pie recipe made with ice cream, but this old-fashioned cake version is made with a moist chocolate Texas sheet cake topped with a layer of chopped pecans, marshmallows, and cooked chocolate icing.
Why I Love This Recipe
- It’s made completely from scratch, but still so easy to make!
- This classic Southern dessert is perfect for ANY occasion.
Ingredients Notes
Find the full printable recipe with specific measurements below.
- Salted butter: Used in both the cake and the icing. Cut it into slices so it melts faster. If you only have unsalted butter add 1/4 teaspoon for each 1/2 cup butter called for.
- Unsweetened cocoa powder: Also needed for both the cake and the icing. This gives it a rich chocolately flavor, especially once the hot water helps it to bloom.
- Sour cream: Adding sour cream (or Greek yogurt) gives the cake crumb a soft, tender, and moist texture.
- Powdered sugar: Used to sweeten the icing and also gives it a bit of structure once it sets. You may find it labeled confectioners’ sugar at the store.
- Mini marshmallows and chopped pecans: The pecans are optional!
How to Make Mississippi Mud Cake
Start by whisking together the flour, sugar, baking soda, and salt in a large bowl.
In a saucepan, melt the butter with water and cocoa powder over medium heat until it comes to a light boil. Remove from the heat, let it sit for a minute or two, then stir it into the dry ingredients.
Add in the sour cream, vanilla, and eggs, then mix until smooth. Pour the batter into a buttered half sheet pan and bake at 350°F for 18–20 minutes.
While the cake bakes, make the icing. Simmer butter and cocoa powder in a saucepan, then whisk in the milk, vanilla, and salt. Stir in powdered sugar until smooth, thinning with a bit more milk if needed. Fold in chopped nuts, if using. Move quickly as it will harden.
As soon as the cake comes out of the oven, top with mini marshmallows and broil for about 1 minute until puffed. Then pour the warm frosting over the top and gently spread it out. Let the cake cool before cutting into squares.
Recipe Tips
- Don’t skip buttering the pan. The grease prevents the marshmallows from sticking.
- The marshmallows shouldn’t melt or burn (we’re not roasting them!), they should be just soft enough that they can still hold up to a layer of frosting.
- Start making your icing halfway through the cake’s baking time so it’s ready to pour on when the cake comes out of the oven.
- For clean slices, use a plastic knife to cut, or spray your cake knife with cooking spray.
More sheet cake recipes to try include white Texas sheet cake, strawberry sheet cake or banana bars.
More Chocolate Cake Recipes
Mississippi Mud Cake
Video
Ingredients
Cake:
- 2 cups all-purpose flour
- 2 cups granulated sugar
- 1 teaspoon baking soda
- ¾ teaspoon fine sea salt or table salt
- 1 cup salted butter , sliced
- 1 cup water
- ¼ cup unsweetened cocoa powder
- ⅔ cup sour cream
- 2 large eggs , whisked
- 1 Tablespoon vanilla extract
Icing:
- ½ cup salted butter , sliced
- ⅓ cup unsweetened cocoa powder
- ⅓ cup milk
- 1 ½ teaspoon vanilla extract
- 3 ½ – 4 cups sifted powdered sugar
- ¼ teaspoon salt
- 10 ounces mini marshmallows
- ½ cup finely chopped pecans , can omit if preferred
Instructions
Chocolate cake
- Preheat the oven to 350°F. Butter a half sheet pan (18×13 inches) and set aside.
- In a large bowl combine 2 cups flour, 2 cups sugar, 1 teaspoon baking soda and 3/4 teaspoon salt. Set aside.
- Heat 1 cup butter, 1 cup water and 1/4 cup cocoa in a medium saucepan over medium heat. Bring to a light boil and then remove from heat and let sit 2 minutes. Then pour into the flour mixture. Stir until combined.
- Stir in 2/3 cup sour cream, 1 Tablespoon vanilla and 2 eggs. Pour mixture into prepared pan.
- Bake for 18-20 minutes, or until a toothpick comes clean. Around 15 minutes in, start making the icing.
- Once the cake is done sprinkle the marshmallows over the top of cake and broil for 1 minute.
Chocolate icing
- Melt 1/2 cup butter in a medium saucepan over low heat. Stir in 1/3 cup cocoa powder. Once the mixture has melted and comes to a light simmer, remove from heat and slowly whisk in 1/3 cup milk, 1 1/2 teaspoon vanilla and a 1/4 teaspoon of salt.
- Slowly stir in 3 1/2 cups sifted powdered sugar. Add an additional 1/4 cup powdered sugar or thin with 2-3 Tablespoons more milk if needed for desired consistency. Fold in nuts if using.
- Evenly pour the icing over the cake with marshmallows immediately when after the cake comes out of the oven. Move quickly to gently spread out evenly with a rubber spatula. The icing will begin to harden.
- Allow to cool and then cut into squares.
Last step: Please leave a comment and rating after you make the recipe.
Notes
Nutrition
Nutrition provided is an estimate. It will vary based on specific ingredients used.
Substitutions and Variations
- Omit the nuts, if preferred. Or, swap the pecans for walnuts.
- You can spread marshmallow fluff on the cake instead of marshmallows if desired.
- I use miniature marshmallows, but you can go ahead and use regular ones.
- Try toasted pecans first for added nuttiness and crunch.
- Cut the recipe in half for a smaller cake. Use a 9×13″ baking dish.
Recipe FAQs
Keep it stored in an airtight container in the fridge for up to 3 days. It can stay out at room temperature for a couple of hours the day it’s made, but overnight it should be kept in the fridge.
Yes! Cover it in a freezer-safe container or wrap it in plastic wrap inside a freezer bag to keep it frozen for up to 3 months. Thaw before serving.
It’s a great make-ahead dessert. Once baked and cooled, cover it with plastic wrap and keep refrigerated for up to 2 days in advance.
Alisha
The cake had fantastic taste and my family really loved the texture from the pecans and marshmallows. – Alisha, recipe tester
Sarah @IHeartNaptime
Thank you for the review of the Mississippi mud cake! Glad your family loved it and you could make the icing work!