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This Southern chocolate delight packs multiple layers of rich flavor with gooey marshmallow and fudgy chocolate that'll make your taste buds dance. The magic happens when that glossy frosting dribbles down through the fluffy marshmallows, creating a dessert that nobody can turn down thanks to its moist base and triple chocolate punch.
I whipped this up for my kid's birthday after he asked for "the most chocolate-packed cake ever" and now we can't have a family party without it. I never get tired of watching guests' eyes light up when they spot those marshmallows poking through the icing.
Ingredients
- All purpose flour: Creates just the right foundation for this soft yet sturdy treat
- Granulated sugar and light brown sugar: Team up to add sweetness while keeping everything moist
- Unsweetened cocoa powder: Packs a chocolate punch without going overboard on sweetness
- Baking powder and baking soda: Make sure your cake puffs up perfectly
- Oil: Makes the cake way juicier than butter would and helps it stay fresh longer
- Eggs: Keep everything together and add a rich texture
- Vanilla extract: Makes the chocolate taste even better
- Milk and sour cream: Give a soft texture and slight tang that cuts through sweetness
- Boiling water: Wakes up the cocoa powder to release its full chocolate power
- Mini marshmallows: Create that signature sticky middle section
- Butter-based frosting: Poured on top to create the classic "mud" look
Step-by-Step Instructions
- Prepare the Baking Pan:
- Get your oven hot at 350°F and completely coat your 9x13 pan with cooking spray. Don't forget those corners where cake loves to stick.
- Mix the Dry Ingredients:
- Throw your flour, sugars, cocoa, baking powder, baking soda, and salt into a big bowl and whisk them really well. If you spot any brown sugar chunks, just squish them with your fingers.
- Combine Wet Ingredients:
- Pour in your oil, eggs, vanilla, milk, and sour cream with the dry stuff and mix until they've just come together. Your batter will look pretty thick now but that's totally fine. Don't forget to scrape the bowl sides.
- Add Boiling Water:
- Keep your mixer on low and slowly add that boiling water. The batter will thin out a lot. Crank up the speed for exactly one minute. This puts air in the mix and makes the cocoa taste way better. Your batter will seem really runny but don't worry about it.
- Bake to Perfection:
- Dump the batter into your pan and let it bake around 40 minutes. Start checking at 38 by poking it with a toothpick. You want a few moist crumbs stuck to it, not wet batter.
- Add Marshmallow Layer:
- Right when the cake comes out hot, cover the whole top with mini marshmallows in a single layer. Pop it back in the oven for 3 minutes so they get puffy but not brown. This helps them stick to the cake.
- Create the Frosting:
- Melt butter in a pot, then mix in milk and cocoa powder. Cook for 2 minutes while stirring the whole time. Take it off the heat and add vanilla and powdered sugar. Use a mixer to get it really smooth. It should pour easily but not be too thin.
- Finish with Frosting Drizzle:
- Pour the warm frosting over the marshmallows so it runs down between them and makes that muddy look. Stick it in the fridge briefly to help the frosting set up.
This treat always takes me back to summer days at my grandma's place in Mississippi when she'd bake this for our family Sunday dinners. She always told me to "never cheap out on cocoa powder because chocolate is the star of the show." Every time I make this rich dessert, I remember her words.
Make-Ahead Magic
The cake gets better after sitting around for a day as all the flavors mix together and the marshmallow settles in with the frosting and cake. For the best taste, make it the day before you'll serve it. You can even bake the cake part two days early and keep it covered on your counter, then add the marshmallows and frosting the next day.
Perfect Slicing Technique
For nice clean cuts, run your knife under hot water and dry it between slices. Those marshmallows can get sticky and mess up your knife. Try cutting at a slight angle through the marshmallow part instead of straight down, which can squish your cake.
Seasonal Variations
During Christmas you can sprinkle crushed candy canes on the warm frosting or add colorful sprinkles for birthday celebrations. In summer, try serving it with a scoop of vanilla ice cream on the side so you get that awesome hot and cold mix with the dense cake.
The Southern History
This cake got its name because it looks like the muddy Mississippi River banks with the chocolate frosting standing in for mud and marshmallows looking like foam floating on top. Home cooks came up with it back in the mid-1900s, and it quickly became a must-have at community potlucks and family get-togethers across the South, showing how creative folks can be with simple ingredients.
Frequently Asked Questions
- → Why add hot water to the mix?
Hot water brings out the cocoa's essence, making the cake more flavorful and giving it a softer texture.
- → What's the best way to store it?
Keep it covered at room temperature for two days, or refrigerate for extra freshness and a longer shelf life.
- → Can I swap mini marshmallows with big ones?
Sure! Just cut the big ones into pieces so they melt evenly across the cake.
- → What works instead of sour cream?
Plain yogurt or buttermilk can replace sour cream, keeping the batter creamy and slightly tangy.
- → How do I change the frosting thickness?
Make it thicker with more powdered sugar, or thinner with a dash of milk for easier pouring.