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A fork taking a bite out of a piece of Mississippi mud cake on a plate.

Mississippi Mud Cake

A rich chocolate sheet cake topped with melted marshmallows, a fudgy frosting, and toasted pecans.
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Prep Time 15 minutes
Cook Time 30 minutes
Total Time 45 minutes
Course Dessert
Cuisine American
Servings 24

Ingredients
  

For the Cake

  • 2 cups granulated sugar 400g
  • 1 cup unsalted butter melted, 227g
  • 4 large eggs
  • 1 ½ cups all-purpose flour 180g
  • ½ cup unsweetened cocoa powder 50g
  • 1 ½ cups toasted pecans chopped, divided, 170g
  • 1 tsp vanilla extract
  • ⅛ tsp salt

For the Topping and Frosting

  • 1 bag (280g) miniature marshmallows 10-ounce
  • 1 lb powdered sugar 450g
  • ⅓ cup unsweetened cocoa powder 35g
  • ½ cup whole milk 120ml
  • ¼ cup unsalted butter softened, 57g

Instructions
 

  • Preheat your oven to 350°F (175°C). Grease and flour a 15x10-inch baking pan.
  • In a large bowl, whisk together the granulated sugar, melted butter, eggs, vanilla extract, and salt until smooth.
  • Stir in the flour and ½ cup of cocoa powder until just combined. Fold in 1 cup of the chopped toasted pecans.
  • Pour the batter into the prepared pan and spread it evenly. Bake for 20 to 25 minutes, or until a toothpick inserted into the center comes out clean.
  • Remove the cake from the oven and immediately sprinkle the miniature marshmallows in an even layer over the top. Return to the oven and bake for 3 to 5 more minutes, just until the marshmallows are soft and slightly puffed.
  • While the cake is in the oven, prepare the frosting. In a medium bowl, use an electric mixer to beat the powdered sugar, ⅓ cup cocoa powder, whole milk, and softened butter until smooth and creamy.
  • Remove the cake from the oven. Pour the warm frosting over the melted marshmallow layer and spread it gently.
  • Sprinkle the remaining ½ cup of toasted pecans over the frosting.
  • Let the cake cool completely in the pan on a wire rack before cutting and serving. This allows the layers to set.

Notes

To toast pecans, spread them on a baking sheet and bake at 350°F (175°C) for 5 to 7 minutes until fragrant. Let them cool before chopping.
If you don't have a 15x10-inch pan, you can use a 9x13-inch pan. The cake will be thicker, so increase the initial baking time to 30-35 minutes.
The frosting is meant to be pourable. If it seems too thick, add another tablespoon of milk. If it seems too thin, add a bit more powdered sugar.
Baked goods containing eggs are considered fully cooked when a toothpick inserted into the center comes out clean.
Keyword chocolate cake, marshmallow, mississippi mud cake, pecan, Sheet Cake