Mississippi Mud Cake

Ingredients

Serves 12–16

The Cake

2 cups (250 g) all-purpose flour, spooned and leveled

1½ cups (300 g) granulated sugar

½ cup (100 g) packed dark brown sugar (adds molasses depth)

½ cup (50 g) unsweetened cocoa powder (Dutch-process for richness)

1 Tbsp baking soda

1 Tbsp baking powder

¼ tsp fine sea salt

2 large eggs, room temperature

½ cup (120 ml) neutral oil (canola or vegetable—keeps cake moist)

1 tsp pure vanilla extract

1 cup (240 ml) boiling water

6 Tbsp (90 ml) whole milk, room temperature

3 Tbsp (45 g) full-fat sour cream (not “lite”—fat = tenderness)

The Marshmallow Layer

1 (10 oz) bag mini marshmallows (~6 cups)

The Fudge Frosting

1 cup (226 g) unsalted butter

6 Tbsp (90 ml) whole milk

2 Tbsp (10 g) unsweetened cocoa powder

3 cups (360 g) powdered sugar, sifted

1 tsp pure vanilla extract

Pinch of salt

Step-by-Step Instructions

1. Prep & Preheat

Position oven rack in center. Preheat to 350°F (175°C).

Grease a 9×13-inch metal baking pan; line with parchment (overhang on long sides). Metal ensures even bake.

2. Whisk Dry Ingredients

In a large bowl, whisk flour, granulated sugar, brown sugar, cocoa, baking soda, baking powder, and salt until no lumps remain.

3. Mix Wet Ingredients

In a medium bowl, whisk eggs, oil, vanilla, milk, and sour cream until smooth.

Pour wet into dry; stir with a silicone spatula just until combined.

Slowly stir in boiling water—batter will be thin. This is normal.

4. Bake the Cake

Pour batter into pan. Bake 28–30 minutes—until a toothpick inserted in center comes out with moist crumbs (not wet batter). Edges will pull from pan.

Cool in pan 5 minutes.

5. Add Marshmallows

Scatter marshmallows evenly over hot cake.

Return to oven 2–3 minutes—until marshmallows puff and just begin to melt. Do not brown.

Cool 30 minutes (marshmallows set slightly).

6. Make the Frosting

In a saucepan, melt butter over medium. Whisk in milk and cocoa; heat 2 minutes—until smooth and glossy. Do not boil.

Pour into a heatproof bowl; cool 10 minutes.

With electric mixer, beat in powdered sugar, vanilla, and salt until thick, smooth, and spreadable (~2 min). Too thick? Add 1 tsp milk.

7. Frost & Serve

Spread frosting over cooled marshmallow layer.

Cool 1–2 hours (frosting sets into fudge-like shell).

Serve: Slightly warm (gooey center) or room temp (firm slice).

Tips for Perfect Gravy

✅ Boiling water is key—activates cocoa, ensures fudgy crumb.

✅ Don’t overbake—center should jiggle slightly when shaken.

✅ Cool marshmallows 30 min—prevents frosting from melting.

(Note: This cake is the dessert—but for extra decadence, drizzle with warm caramel and crushed pecans.)

Serving Suggestions

With vanilla ice cream and hot fudge

As a base for s’mores sundaes (add graham cracker crumbs)

Paired with a bold Cabernet Sauvignon or cold espresso

Storage & Make-Ahead Tips

Keep airtight at room temp 3 days, or refrigerated 5 days.

Freeze unfrosted up to 3 months—thaw, then frost.

Do not freeze frosted—frosting weeps.

Frequently Asked Questions

Can I use light brown sugar?

Yes—but dark adds deeper flavor.

No sour cream?

Sub 3 Tbsp plain Greek yogurt.

Make it gluten-free?

Use 250 g GF 1:1 flour (like King Arthur) + ¼ tsp xanthan gum.

Allergy Information

Contains: Dairy, eggs, wheat.

Nut-free, soy-free (check cocoa label), fish/shellfish-free.

Gluten-free option: See above.

Nutrition Facts

(Per slice, 1 of 12)

There’s quiet magic in the alchemy of cocoa, sugar, and heat—transforming simple pantry staples into something that tastes like memory itself. As you break through the crackly frosting into the molten marshmallow and fudgy cake beneath, you’ll taste more than dessert.

You’ll taste tradition: of church suppers, of summer nights, of the kind of generosity that fills a 9×13 pan and says, “There’s enough for everyone—and then some.”

So bake it generously. Serve it warmly. And savor the kind of joy that doesn’t need grandeur—

just chocolate, marshmallows, and a whole lot of Southern soul.