Mississippi Mud Cake

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 more well suited for a scoop of ice cream on top.

It’s a classic Southern dessert that gets its name from resembling the rock and mud of the Mississippi River. A moist chocolate Texas sheet cake is topped with a layer of chopped pecans, marshmallows, and cooked chocolate icing for a gooey crowd-pleaser!

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: Regular marshmallows can be used and the pecans are optional or you can swap with walnuts instead.

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.
• Replace water with coffee for a more intense chocolate taste.
• 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.
• Cut the recipe in half for a smaller cake. Use a 9×13″ baking dish.