Mississippi Mud Cake Recipe

This easy Mississippi mud cake is a crowd-pleasing chocolate sheet cake topped with marshmallows and rich chocolate icing.

Course Dessert

Cuisine American

Prep Time 20

Cook Time 25

Total Time 45

Servings servings

Calories 348kcal

Preheat oven to 350 F. Grease a cookie sheet (I use a 15×11-inch rimmed cookie sheet/jelly roll pan) with edges. Set aside.
Melt butter in a large saucepan.
½ cup salted butter
Once butter has melted, stir in water and cocoa powder; bring to a boil.
¼ cup unsweetened cocoa powder, 1 cup water
Once at a boil, add buttermilk, and stir to combine. Remove pan from heat.
½ cup buttermilk
Add the sour cream, eggs, and vanilla, and stir until well-combined.
¼ cup sour cream, 2 large eggs, 1 teaspoon vanilla extract
Stir in flour, sugar, baking soda, and salt until just combined.
2 cups all-purpose flour, 1 ¼ cups granulated sugar, 1 teaspoon baking soda, ½ teaspoon salt
Bake for 15-20 minutes.
Sprinkle marshmallows over the cake and return to the oven for about 3 minutes.
10 ounce bag mini marshmallows
While the cake is baking, prepare the icing.
For the icing, combine the butter, cocoa, and buttermilk. Bring to a boil.
½ cup salted butter, ¼ cup unsweetened cocoa powder, ⅓ cup buttermilk
Remove from heat, and add the powdered sugar, vanilla. Stir to combine.
3 cups powdered sugar, 1 teaspoon vanilla
Stir pecans into icing, if using.
1 cup chopped pecans
Pour icing over hot cake and spread evenly over cake.
Let the cake sit for at least 30 minutes for the frosting to set up.

Salted butter: If using unsalted butter, increase the salt to 1 teaspoon.
Buttermilk: You can make a quick substitute with this buttermilk substitute recipe.
Sour cream: Plain Greek yogurt makes a good substitute.
Flour: To properly measure the flour either weigh it or sift or stir to break it up, lightly spoon into a measuring cup, and level. Avoid packing the flour as that will give you heavy, dry cake.
Nutrition values are estimates.