If you love rich chocolate desserts, these Oven-Baked 5-Ingredient Mississippi Mud Bars are sure to become a favorite. They feature a soft, fudgy chocolate base topped with fluffy marshmallows and a smooth chocolate frosting. Every bite is sweet, gooey, and wonderfully chocolatey.
This easy version uses just five main ingredients, making it a convenient dessert for potlucks, family gatherings, bake sales, or weekend treats. No complicated techniques are needed, and the bars are easy to prepare in one baking pan.
Why You’ll Love These Mississippi Mud Bars
- Only five ingredients: A simple dessert made with easy-to-find ingredients.
- Rich chocolate flavor: The chocolate cake mix creates a deliciously soft base.
- Gooey marshmallow topping: Mini marshmallows melt slightly over the warm bars.
- Easy to prepare: No special equipment or complicated steps.
- Perfect for sharing: One pan makes plenty of dessert squares.
Ingredients
- 1 box (15.25 ounces) chocolate cake mix
- 2 large eggs
- 1/2 cup unsalted butter, melted
- 3 cups mini marshmallows
- 1 container (16 ounces) chocolate frosting
These five ingredients create a simple shortcut version of classic Mississippi mud bars.
Instructions
Step 1: Prepare the Baking Pan
Preheat your oven to 350°F (175°C). Grease a 9-by-13-inch baking pan or line it with parchment paper, leaving some overhang for easy removal.
Step 2: Make the Chocolate Base
In a large mixing bowl, combine the chocolate cake mix, eggs, and melted butter. Stir until a thick, uniform dough forms.
The mixture will be thicker than traditional cake batter. This is exactly what you want for a soft, brownie-like bar base.
Step 3: Press and Bake
Transfer the chocolate mixture into the prepared pan. Press it evenly into the bottom using a spatula or lightly greased hands.
Bake for approximately 15–18 minutes, until the base is set.
Step 4: Add the Marshmallows
Remove the pan from the oven and immediately sprinkle the mini marshmallows evenly over the warm chocolate base.
Return the pan to the oven for another 2–3 minutes, just until the marshmallows become soft and puffy.
Step 5: Finish with Chocolate Frosting
Remove the pan from the oven and let it rest for about 5 minutes. Gently spread the chocolate frosting over the warm marshmallow layer. The warmth will help the frosting soften and spread more easily.
Allow the bars to cool completely before slicing.
Tips for the Best Mississippi Mud Bars
- Don’t overbake the base: The chocolate layer should remain soft and fudgy.
- Spread the marshmallows evenly: This gives every bar a gooey topping.
- Work while the bars are warm: The marshmallows soften nicely, making the frosting easier to spread.
- Cool before cutting: This helps the layers set and creates neater squares.
- Use parchment paper: It makes lifting the cooled bars out of the pan much easier.
Easy Variations
Peanut Butter Mississippi Mud Bars: Swirl a little creamy peanut butter into the chocolate frosting before spreading.
Extra Chocolate Flavor: Use chocolate fudge frosting for an even richer topping.
Nutty Mud Bars: Sprinkle chopped pecans or walnuts over the frosting. These are optional additions and are not included in the five-ingredient recipe.
Dark Chocolate Version: Choose a dark chocolate cake mix and dark chocolate frosting for a deeper chocolate flavor.
How to Serve
These bars are delicious served at room temperature with a glass of cold milk or a cup of coffee.
For an extra-special dessert, serve a square slightly warmed with a scoop of vanilla ice cream. They also make a wonderful addition to holiday dessert trays, birthday celebrations, and potluck tables.
Storage Instructions
Room Temperature: Store the completely cooled bars in an airtight container for up to 2 days in a cool room.
Refrigerator: Store in an airtight container for up to 5 days. Let the bars sit at room temperature briefly before serving for a softer texture.
Freezer: Freeze individual bars in a freezer-safe container, separating layers with parchment paper, for up to 2 months. Thaw in the refrigerator or at room temperature.
Frequently Asked Questions
Can I use homemade chocolate frosting?
Yes. Homemade chocolate frosting works beautifully. Use approximately 2 cups of prepared frosting.
Can I use large marshmallows?
Yes. Cut them into smaller pieces so they cover the chocolate base more evenly.
Why is my chocolate base crumbly?
The mixture should be pressed firmly into the pan before baking. Also, make sure you measure the melted butter accurately.
Do I need to refrigerate Mississippi Mud Bars?
Refrigeration is recommended if your kitchen is warm or if you want the frosting and marshmallow layers to stay firm.
Can I make these bars ahead of time?
Absolutely. Prepare them a day ahead, let them cool completely, and store them covered until ready to serve.
Final Thoughts
These Oven-Baked 5-Ingredient Mississippi Mud Bars bring together everything a chocolate dessert lover could want: a soft chocolate base, fluffy marshmallows, and a smooth chocolate topping.
They’re simple enough for everyday baking but delicious enough to serve at a special gathering. Make a pan, let the layers set, and enjoy a rich, gooey chocolate treat with family and friends.
Recipe Card
Oven-Baked 5-Ingredient Mississippi Mud Bars
Prep Time: 10 minutes
Bake Time: 17–21 minutes
Cooling Time: 1 hour
Total Time: About 1 hour 30 minutes
Servings: 16 bars
Ingredients
- 1 box (15.25 ounces) chocolate cake mix
- 2 large eggs
- 1/2 cup unsalted butter, melted
- 3 cups mini marshmallows
- 1 container (16 ounces) chocolate frosting
Instructions
- Preheat oven to 350°F (175°C). Grease or line a 9-by-13-inch baking pan.
- Mix chocolate cake mix, eggs, and melted butter until a thick dough forms.
- Press the mixture evenly into the prepared pan.
- Bake for 15–18 minutes, until the base is set.
- Sprinkle mini marshmallows over the warm base.
- Bake for another 2–3 minutes, until marshmallows puff.
- Let rest for 5 minutes, then gently spread chocolate frosting over the top.
- Cool completely before cutting into 16 bars.
Storage: Store in an airtight container for up to 2 days at room temperature or up to 5 days refrigerated.