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Old Fashioned Mississippi Mud Cake
Mississippi Mud Cake is a rich chocolate dessert with a dense, brownie-like base, a soft marshmallow layer, and chocolate frosting on top. In the South we expect it to be fudgy. We see people explaining it looks like mud on the top.
No it doesn’t. Whoever says that has never walked through the thick mud in the Delta. As far as we are concerned, the base is the muddy part.
Our recipe is the vintage kind, nothing at all like a fluffy cake or anything made from a box. So expect the “cake” part to be thick as mud. We honestly have no idea why it is called a cake. The only similarity is that it is made in a 9 × 13-inch pan. Maybe the name stuck because plain old Mississippi Mud now turns up recipes for pies and all kinds of other things that are not what we expect in the South when someone says they are serving Mississippi Mud.
Don’t miss the good stuff! Scroll down past the recipe card for helpful Pro Tips and additional information.
Mississippi Mud Cake
Ingredients
Cake
- 1 cup salted butter
- 1/3 cup unsweetened cocoa powder
- 1/2 teaspoon instant coffee or espresso powder optional
- 2 cups granulated sugar
- 4 large eggs
- 1 1/3 cups all-purpose flour
- 1 cup chopped nuts optional
- 1 bag 10 ounces mini marshmallows, or one large jar Marshmallow cream
Frosting
- 1/2 cup butter
- 1/3 cup unsweetened cocoa powder
- 1/2 cup evaporated milk
- 1/2 teaspoon instant coffee of espresso powder optional
- 1 pound powdered sugar about 3 1/2 cups
- 1 cup chopped nuts optional
Instructions
Fudgy Cake Base
- Preheat the oven to 300°F.
- Prepare a 9X13 pan by greasing or spraying with non-stick spray followed by a parchment paper sling and set aside
- Melt the butter over low heat in a small saucepan.1 cup salted butter
- Remove from the heat. Whisk in the cocoa powder and espresso powder, if using, until smooth. Allow the mixture to cool for 10 minutes.1/3 cup unsweetened cocoa powder, 1/2 teaspoon instant coffee or espresso powder
- Add the sugar to a large mixing bowl.2 cups granulated sugar
- Add the cocoa and butter and mix well.
- Add the eggs and beat until fully incorporated.4 large eggs
- Add the flour to the butter mixture a little at a time. Mix until there are no visible flour streaks, scrape the bowl if needed.1 1/3 cups all-purpose flour
- Stir in the chopped nuts, if using.1 cup chopped nuts
- Pour the batter into the prepared pan. Bake for 30 to 40 minutes.
- Remove the cake from the oven and immediately cover with the mini marshmallows. Spread them into an even layer.1 bag
- Return the pan to the hot oven for 3 minutes, just until the marshmallows puff slightly. Watch closely; do not let them brown or puff significantly.
- Remove the cake from the oven and let it cool for 20 minutes. The marshmallows will melt together and firm up enough to keep the frosting from running through them.
Frosting
- Melt the butter in a saucepan over low heat.1/2 cup butter
- Remove from the heat and whisk in the cocoa powder until smooth. Stir in the evaporated milk, and espresso powder, if using.1/3 cup unsweetened cocoa powder, 1/2 teaspoon instant coffee of espresso powder, 1/2 cup evaporated milk
- Return the saucepan to low heat and cook until warm.
- Gradually add the powdered sugar and beat until smooth.1 pound powdered sugar
- Stir in the chopped nuts.1 cup chopped nuts
- Pour the warm frosting evenly over the softened, cooled marshmallows.
- Allow the frosting to set before serving.
Notes
Nutrition
Nutrition information is automatically calculated and may vary based on exact ingredients used. For accuracy, consult a registered dietitian or nutritionist.
Pro Tips
When checking whether the cake is done, insert a toothpick into the center. A few small bits of cake stuck to it are fine. A coating of wet batter means it needs more time. The center should no longer look wet, but you don’t need to keep baking until the toothpick comes out completely clean.
The base is dense and brownie-like. There’s no baking powder or baking soda in this recipe, so you aren’t looking for a light, fluffy cake.
The marshmallows only need about 3 minutes in the oven. They should soften and puff slightly. You don’t want them brown or puffed up too much.
The full 20-minute cooling period matters. The frosting is heavy and will sink through marshmallows that are still too soft. Ask me how I know.
The frosting should be warm enough to pour, but not piping hot. You don’t want to undo that cooling time by pouring hot frosting over the marshmallows. Some of your frosting may leak through no matter what you do, it’s fine!
The nuts are optional. We prefer toasted pecans, and I chop them before toasting for a little extra flavor.
Serving
The cake needs time to set before you slice it. An overnight rest works well and gives all three layers time to firm up.
Storage
Once the cake has cooled and the frosting has set, you can cover the pan tightly or put the pieces in an airtight container. It will keep in the refrigerator for up to 5 days.
The cake needs to come back to room temperature before serving. Straight from the refrigerator, it’s like a solid block. Another thing I learned the hard way.
For longer storage, individual pieces will keep in an airtight freezer container for up to 3 months. Parchment paper between the layers keeps them from sticking together. The cake can thaw overnight in the refrigerator, then come back to room temperature before serving.
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This recipe was written and tested by a human.