This Retro Recipe Is My Favorite Chocolate Cake

With a fluffy chocolate cake, a layer of gooey marshmallow and toasted pecans, and a silky smooth icing, Mississippi mud cake is a family favorite. The Southern retro recipe is easy to make and a complete crowd-pleaser.

Closeup side view of a slice of Mississippi Mud Cake on a white surface and light blue background — Simply Recipes / Photo by Andrew Bui / Food Styling by Kaitlin Wayne

Mississippi mud cake—a relative to the popular Mississippi mud pie—is a Southern classic for good reason. The chocolate sheet cake is topped with a layer of mini marshmallows, sometimes nuts, and cooked chocolate icing. When layered together, the cake resembles the muddy terrain along the Mississippi River and tastes incredibly delicious.

This recipe is low effort and high reward. The cake comes together easily, but a few thoughtful techniques make it taste like you spent hours on it. Aren’t those always the best kinds of desserts?

The cake itself is a true one-bowl situation that’s fuss-free and bakes beautifully plush, light, and lofty every time, acting as the perfect base. The marshmallows create a sweet, bumpy surface for a muddy look, and the little divots perfectly catch the toasted pecans. Finally, though cooking the icing may sound tricky, it’s actually easier than whipped frosting and comes out shiny, silky, and decadently chocolatey.

All the magic comes from the combination of flavors and textures. Perfect for the chocolate fiends among us (raises hand), this cake has a little something for everyone and is easy enough to whip up at a moment’s notice.

Tips for Making Mississippi Mud Cake

Take care to line and grease all sides of the baking pan as the marshmallows get sticky when they are melted slightly.
If your cocoa or powdered sugar is overly lumpy, sift them first.
Though tempting, don’t heat the marshmallows so much that they fully melt and/or toast. This will lead to a thin, sugary layer of marshmallow rather than a thick, pillowy layer that can hold up to the icing.
Avoid making the icing in advance. It will need reheating and can become too thick. It’s quick and easy to make, so whip it up when you’re ready to frost the cake.
Spray your knife with nonstick cooking spray before slicing the cake to help keep the marshmallow from sticking to it for cleaner cuts.

Overhead view of Mississippi Mud Cake in a blue baking dish with a serving utensil and one slice already removed — Simply Recipes / Photo by Andrew Bui / Food Styling by Kaitlin Wayne

Sheet Cake Recipes

Preheat the oven to 350°F.

Arrange a rack in the center of the oven.

Lightly spray a 9x13-inch metal baking pan with nonstick cooking spray.

Make the batter:

In a large bowl, whisk together the hot coffee and cocoa powder until smooth. Let sit to bloom (this helps develop the chocolate flavors) and cool slightly, about 5 minutes.

Overhead view of a hand whisking hot coffee and cocoa powder together in a clear glass bowl for Mississippi Mud Cake recipe — Simply Recipes / Photo by Andrew Bui / Food Styling by Kaitlin Wayne

Add the remaining ingredients:

Add the sour cream, melted butter, oil, eggs, and vanilla to the coffee mixture and whisk until smooth. Add the granulated sugar and whisk to combine.

Add the flour, baking powder, baking soda, and salt and whisk until just combined.

Overhead view of a clear glass bowl with a whisk after mixing the remaining ingredients to the coffee mixture for Mississippi Mud Cake recipe — Simply Recipes / Photo by Andrew Bui / Food Styling by Kaitlin Wayne

Bake the cake:

Scrape the batter into the prepared pan. Bake the cake until risen and a toothpick inserted into the center comes out clean, 25 to 30 minutes. Don’t turn off the oven.

Overhead view of a light blue baking dish of the batter after baking for Mississippi Mud Cake recipe — Simply Recipes / Photo by Andrew Bui / Food Styling by Kaitlin Wayne

Top with the marshmallows and pecans:

Remove the cake from the oven. Sprinkle the mini marshmallows evenly over the cake. There will be gaps between the marshmallows—that’s okay. Return the cake to the oven and bake until the marshmallows are just puffed and some of their definition is lost, closing the gaps, about 2 minutes.

Set the pan on a wire rack. Top the marshmallow layer evenly with 1 cup of the chopped pecans and reserve the remaining 1/3 cup (if using).

Overhead view of a light blue baking dish of the batter after topping with marshmallows and pecans for Mississippi Mud Cake recipe — Simply Recipes / Photo by Andrew Bui / Food Styling by Kaitlin Wayne

Make the icing:

Immediately after topping the cake with pecans, make the icing.

Add the butter to a medium saucepan and melt over medium heat. Add the cocoa powder, milk, vanilla, and salt to the butter and whisk until smooth. Gradually whisk in the powdered sugar until smooth and glossy. Remove from the heat and let cool ever so slightly, 2 to 3 minutes.

Overhead view of a small saucepan and whisk after melting the butter and adding cocoa powder, milk, vanilla, and salt for Mississippi Mud Cake recipe — Simply Recipes / Photo by Andrew Bui / Food Styling by Kaitlin Wayne

Finish the cake:

Give the icing a good stir and then pour it evenly over the cake. Take the time to pour the icing evenly as it’s a bit difficult to spread with a spatula after the fact. Top with the remaining 1/3 cup of pecans (if using).

Allow the cake to cool completely in the pan set over the wire rack before serving. Use a sharp knife lightly sprayed with nonstick cooking spray to slice the cake (this helps to keep the marshmallow from sticking to the knife).

Leftover cake can be stored in an airtight container or in the pan tightly wrapped with plastic wrap at room temperature for up to 4 days.

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