Rich, fudgy chocolate cake topped with gooey marshmallows and a glossy cocoa frosting — this Southern classic is pure indulgence. Perfect for potlucks, holidays, or anytime you’re craving chocolate heaven.
🛒 Ingredients
For the Cake
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2 large eggs
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1 cup whole or 2% milk
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½ cup sour cream
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1 cup plus 1 tablespoon vegetable oil, divided
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2 cups all-purpose flour
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1 cup packed light brown sugar
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1 cup granulated sugar
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½ cup Dutch-processed cocoa powder
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1 ½ teaspoons baking powder
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1 teaspoon baking soda
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1 tablespoon vanilla extract
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½ teaspoon kosher salt
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1 (10-ounce) bag mini marshmallows (about 4 cups)
For the Frosting
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8 tablespoons (1 stick) unsalted butter
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⅓ cup whole or 2% milk
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¼ cup Dutch-processed cocoa powder
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2 teaspoons vanilla extract
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¼ teaspoon kosher salt
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2 ½ cups powdered sugar
👩🍳 Instructions
Step 1 – Prepare the Cake
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Preheat oven to 350°F (175°C). Grease a 9×13-inch baking pan with 1 tablespoon of oil or line with parchment paper.
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In a large bowl, whisk together flour, brown sugar, granulated sugar, cocoa powder, baking powder, baking soda, and salt.
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In another bowl, whisk eggs, milk, sour cream, 1 cup oil, and vanilla extract until smooth.
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Pour wet ingredients into dry ingredients and stir until just combined (do not overmix).
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Spread batter evenly into the prepared pan.
Step 2 – Bake
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Bake for 30–35 minutes, or until a toothpick inserted in the center comes out clean.
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Immediately sprinkle mini marshmallows evenly over the hot cake. Return to oven for 2–3 minutes, just until marshmallows puff and soften. Remove and let cool slightly.
Step 3 – Make the Frosting
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In a medium saucepan, melt butter over medium heat. Stir in milk, cocoa powder, vanilla, and salt.
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Whisk until smooth, then gradually beat in powdered sugar until thick and glossy.
Step 4 – Finish
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Pour warm frosting over the marshmallow layer, spreading gently to cover.
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Let cake cool completely before slicing into squares.
🍽 Tips & Variations
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Add chopped pecans or walnuts on top for crunch.
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Serve slightly warm with a scoop of vanilla ice cream for extra decadence.
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Store leftovers covered at room temperature for 2 days or in the fridge up to 5 days.