Of all the chocolate cakes in all the world, this might just be my favorite. Mississippi Mud Cake is made with a relatively thin layer of moist decadent chocolate cake topped with soft mini marshmallows and blanketed with a thiiiiiick layer of chocolate frosting.
This is a no-fuss, no mixer required, simple recipe that you’re going to love, and of course I have a how-to video!
I’m sharing today’s recipe by popular request, but honestly it almost feels like a cheat.
Mississippi Mud Cake is actually extremely similar to Texas sheet cake, and sometimes they even go by the same name. After some digging, I found that the difference between the two (beyond the geographical location of the states they’re named for) comes down to this: One has marshmallows (👆🏻). The other does not. And… that’s it.
Even though I hesitated to share initially, after transforming my Texas sheet cake into its Eastern sister more than once for myself, I decided it was worth sharing in its own post.
To make this recipe, I used the same chocolate sheet cake (soft, moist, chocolatey and fudgy, no alterations were needed), scattered a generous number of marshmallows overtop, and doubled the chocolate frosting to better accommodate all the bumps and grooves from the marshmallows.
The results were incredible, decadent, and since I’ve received so many requests, worth sharing in their own post (plus, videoing and photographing the cake made for a great excuse to make it two more times!).
Why Is It Called Mississippi Mud Cake?
The surface is said to resemble the dark, mucky banks of the Mississippi river.
How to Make Mississippi Mud Cake
The true beauty of this cake is how easy it is to make. There’s no mixer needed and much of the work is done on the stovetop. This is just an overview of the process, for the full step-by-step instructions please scroll down to the recipe card.
- Heat butter, water, and cocoa powder together on the stovetop until melted. Combining the cocoa powder with this hot liquid blooms it (I talked about this before in my chocolate cake recipe) and gives the cake its rich chocolate flavor.
- Combine your dry ingredients (including sugars) in a separate large bowl. Make a well in the center and whisk together sour cream, eggs, and vanilla. Stir to combine, the batter will be very thick at this stage, that’s normal!
- Carefully pour the chocolate mixture into your thick batter and stir until everything is smooth. Pour into a lightly greased jelly roll pan and transfer to your oven to bake until cooked through.
- While the cake is cooking, prepare your frosting by melting together butter and milk. Add cocoa powder, salt, and vanilla extract and stir well, then add powdered sugar until you have a smooth icing.
- When cake is finished baking, lightly press 10 oz of mini marshmallows over the surface, then drizzle the frosting evenly over the top of the marshmallows. You may have some marshmallows poking through still, this is fine, or if you’d like you can use a spatula to gently try to spread the frosting immediately after pouring.
The hardest part is waiting for the icing to harden before you can dig in!
- Add pecans! Some Mississippi Mud Cakes incorporate pecans (which makes the whole thing a lot like a rocky road cake). Substitute a cup of the marshmallows for a heaping cup or so of coarsely chopped pecans, or just sprinkle pecans over the top.
- When adding the mini marshmallows to the top of the cake, very gently press them against the surface to encourage them to stick. The frosting will hold them on, but gently pressing helps (don’t smash your cake, though!).
- Measure your powdered sugar (for the frosting) the same way you would measure flour (or better yet use a scale like this one!). Don’t pack it into the cup or your frosting will be too thick.
- Begin preparing the frosting while the cake is still cooking, ideally you’d time it so the frosting is finished within 5 minutes of the cake coming out of the oven and pour it over the cake while both are still warm.
I always leave my mud cake in the jelly roll pan that I baked it in, as transferring it would be difficult and the cake would most likely fall apart (unless you cut it and move it piece by pice). To store, cover with plastic wrap and keep at room temperature for up to 4-5 days. The cake may be refrigerated if you prefer it cold, and would keep up to a week in the fridge. Personally I think it’s best at room temperature.
More Recipes for Chocoholics:
Let’s bake together! Don’t forget to watch the how-to VIDEO in the recipe card!
Mississippi Mud Cake
- 1 cup unsalted butter 226g, cut into pieces
- 1 cup water 235ml
- 1/3 cup cocoa powder 35g
- 2 cups all-purpose flour 250g
- 1 ½ cups granulated sugar 300g
- ½ cup light brown sugar firmly packed (100g)
- 1 teaspoon baking soda
- 3/4 teaspoon salt
- 1/2 teaspoon instant coffee optional
- 1/2 cup sour cream 125g
- 2 large eggs room temperature lightly beaten
- 1 teaspoon vanilla extract
- Preheat your oven to 350F/175C and lightly grease and flour a 10x15 jelly roll pan (or spray with baking spray).
- In a medium-sized saucepan, combine butter, water, and cocoa powder. Turn heat to medium low and stir occasionally until butter is melted.
- Increase heat to medium-high and (stirring frequently) bring to a rolling boil. Remove from heat and allow to cool for 15-20 minutes.
- Meanwhile, whisk together flour, sugar, baking soda, salt, and instant coffee (if using) in a large bowl. Make a well in the center and add sour cream, eggs, and vanilla extract. Whisk together sour cream/eggs/vanilla in the well, then use a spatula to combine all ingredients in the bowl (mixture will be thick).
- Add slightly cooled chocolate mixture to the flour mixture and stir until well-combined (be careful, chocolate mixture will still be a bit hot).
- Pour batter into prepared pan and carefully (don’t spill!) transfer to 350F (175C) oven. Bake for 20-25 minutes or until toothpick inserted in center comes out clean or with a few moist crumbs, but while cake is baking measure out your marshmallows and prepare frosting.
- Prepare frosting by combining milk and butter in large heatproof bowl and microwave, stirring every 15 seconds, until melted and mixture is warm. Sift in cocoa powder and whisk until combined.
- Gradually sift in powdered sugar and whisk until smooth. Stir in vanilla extract.
- Once cake has finished baking, pour mini marshmallows evenly over the top and very gently press them against the surface of the cake (don’t smash the cake!). Pour chocolate frosting evenly over the cake.
- Allow cake to cool and frosting to set, about 1-2 hours, before cutting and enjoying.