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You are going to love this old fashioned Mississippi Mud Cake recipe is! Perfectly moist chocolate cake is topped with mini marshmallows that are melted and topped with an easy peasy chocolate icing.

Close up side view of one piece of Easy Mississippi Mud Cake so the marshmallow layer and icing layer are visible.

What makes my Mississippi Mud Cake such an easy recipe? I use a boxed cake mix that is transformed into tasting homemade by using a few tricks I’ve learned over the years. By swapping the ingredients called for on the box with some better options we can make a store bought mix taste like a homemade cake.

I mix this cake by hand so no stand mixer bowl or electric mixer beaters to wash. The creamy frosting is also made by hand. It kinda reminds me of the frosting that is on a Texas Sheet Cake or Lunch Lady Brownies.

The entire Easy Mississippi Mud Cake that was made with a boxed cake mix before it has been cut.

Jump to:

What is Mississippi Mud Cake?
Ingredient Notes
How to make Mississippi Mud Cake
Tips
Storage
Easy Mississippi Mud Cake Recipe (with boxed cake mix)
More dessert recipes…

The cut cake in the cake pan so the cake and layers are visible.

What is Mississippi Mud Cake?

Mississippi Mud Cake is a rectangular chocolate cake that is topped with a layer of miniature marshmallows, or marshmallow creme, and a layer of chocolate frosting or icing. It’s a chocolate lover’s dream!

There are a couple of theories about where the name comes from. One is that a resident of Greenville, Mississippi compared a Mississippi Mud Pie to the color of the mud leftover by the flooding of the Mississippi River. The other theory suggests it became popular during World War II because the ingredients used to make it were readily available.

This decadent chocolate cake is a favorite dessert that is served on special occasions, potlucks and family gatherings throughout the South.

One piece of cake on a white plate, the layers are visible as well as the inside of the chocolate cake.

Ingredients

See recipe card for exact amounts and full recipe.

Ingredient Notes

cake mix – milk chocolate, Devil’s food, or chocolate fudge are all great options. You will not need the exact ingredients specified on the box.

milk – I use whole milk but you can use low-fat milk, or even dairy free milk, if that is what you have on hand.

eggs – we use large room temperature eggs.

melted butter – unsalted butter is used in the cake instead of oil and also in the frosting.

mini marshmallows – the mini ones are the perfect size to top the cake, they melt fast and will result in a nice even-ish layer of gooey marshmallows. I have not made this recipe using marshmallow cream.

cocoa – unsweetened cocoa powder is what gives our frosting rich chocolate flavor.

powdered sugar – this is the base for many great frostings and toppings. You can make your own powdered sugar if you have granulated sugar and cornstarch, Good Housekeeping tells you how, so check that out if you don’t have powdered sugar.

vanilla extract – we use pure vanilla extract and not vanilla flavoring.

Just half of the uncut cake is visible, it is in a turquoise colored Wilton cake pan.

How to make Mississippi Mud Cake

Melt the butter for the cake in a small saucepan or skillet over low heat, allow to cool completely. See tips below.
Preheat the oven to 350° and coat a 9″ X 13″ pan with nonstick cooking spray.
In a large bowl mix the cake mix, eggs, milk and melted butter together with a whisk or large spoon. Pour the cake batter into the prepared pan and bake for 28-33 minutes or until a toothpick inserted into the center comes out clean. The top of the cake will spring back when touched and the sides will pull away from the pan when the cake is done.
Sprinkle marshmallows onto the hot cake in an even layer, put back in the oven and bake until the marshmallows just start to brown, about 3-5 minutes. This time may vary so watch them closely so they don’t burn. Let cool completely.
Melt the butter and make the frosting by placing all of the ingredients into a large mixing bowl and mixing with a whisk or large spoon. Pour the warm icing over the marshmallows and spread into an even layer using a spatula or spoon. For best results cool completely so the icing sets up before cutting and serving.

A collage of 10 images showing the different steps to make this Easy Mississippi Mud Cake Recipe (with box cake).

Tips

Melt butter for the cake mix and frosting separately.
When you melt the butter for the cake take the eggs and milk out of the fridge and let them come to room temperature while the butter cools. The butter will be cool and the eggs and milk will be room temp after about 30-45 minutes, depending on the temperature in your house.
Cool the cake on a cooling rack on a counter that is away from the warm oven. This is an important step! The first time I made this cake I didn’t let the cake and marshmallow topping cool long enough and when I poured the icing over it I just ended up with a mess. We still ate it but it didn’t look good and I didn’t have one layer of marshmallows and one layer of icing, they sort of mixed together. It was still tasty but not what I wanted.
I always sift my powdered sugar and cocoa to get any large lumps out so my icing is as smooth as possible. I do this by putting them into a mesh strainer and pushing it through with the back of a large spoon.

One piece of Easy Mississippi Mud Cake is on a white plate, the cake pan is in the background.

Variation

There are versions of this cake that include pecans for a little crunch. Add about 1 cup of toasted chopped pecans either on top of the marshmallow layer before you add the icing or on top of the icing.

Storage

Store in an airtight container at room temperature or in the refrigerator for 3 or 4 days. A quick google search suggests that this cake can be frozen for up to 3 months in individual servings or as a whole. Defrost completely before serving.

I personally have not frozen this cake before but have frozen other cakes that were great when defrosted.