Bumpy Chocolate Fudge Cake

A throwback to the comforting sheet cakes of my childhood, this Bumpy Chocolate Fudge Cake combines a rich and moist chocolate base with creamy vanilla buttercream ridges—topped off by a silky, pourable fudge icing. It’s a nostalgic dessert that’s equal parts fun, indulgent, and crowd-pleasing.

Why You’ll Love This Recipe

I love how this cake layers texture and flavor in the most delightful way. The fudgy chocolate cake itself is tender and not too sweet, which perfectly balances the rich icing and buttery vanilla bumps on top. It’s a conversation starter at parties and potlucks, and the sheet cake format makes it super simple to serve. Whether I’m baking for a special occasion or just need a hit of comfort food, this one always delivers.

Ingredients

(Tip: You’ll find the full list of ingredients and measurements in the recipe card below.)

For the Cake:

2 cups all-purpose flour

1 ½ cups granulated sugar

½ cup unsweetened cocoa powder

1 teaspoon baking soda

1 teaspoon baking powder

½ teaspoon salt

1 cup buttermilk

½ cup unsalted butter, melted

2 large eggs

1 tablespoon vanilla extract

For the Vanilla Buttercream Ridges:

½ cup unsalted butter, softened

2 cups powdered sugar

1 tablespoon milk

1 teaspoon vanilla extract

For the Warm Fudge Icing:

½ cup unsalted butter

½ cup unsweetened cocoa powder

⅓ cup milk

3 cups powdered sugar

1 teaspoon vanilla extract

Directions

I start by preheating my oven to 350°F (175°C) and greasing a 9×13-inch baking pan.

In a large bowl, I whisk together the flour, sugar, cocoa powder, baking soda, baking powder, and salt.

I add the buttermilk, melted butter, eggs, and vanilla extract to the dry ingredients, then mix until the batter is smooth and well combined.

I pour the batter into the prepared pan and bake it for 25 to 30 minutes, or until a toothpick inserted in the center comes out clean. Once baked, I let the cake cool completely.

For the vanilla buttercream, I beat softened butter until creamy, then add powdered sugar, milk, and vanilla. I beat this until the frosting becomes fluffy.

Using a piping bag, I pipe long, thick ridges of buttercream across the cooled cake to create the signature “bumps,” then chill it for about 10 minutes so the buttercream firms up.

For the fudge icing, I melt the butter in a saucepan over medium heat, then whisk in cocoa powder and milk.

I remove the pan from heat and beat in powdered sugar and vanilla until the icing is smooth and pourable.

Then I pour the warm fudge icing evenly over the cake, letting it flow naturally around the buttercream ridges.

I chill the finished cake for at least 1 hour before slicing to allow the icing to fully set.

Servings and timing

This recipe yields 12 servings.

Prep Time: 20 minutes

Cooking Time: 30 minutes

Total Time: 50 minutes

Calories: Approximately 415 kcal per serving

Variations

I sometimes swap the vanilla buttercream with a flavored version—almond or peppermint extract can give it a fun seasonal twist.

For a deeper chocolate flavor, I use dark cocoa powder in both the cake and icing.

I’ve also added a layer of mini chocolate chips or chopped nuts between the buttercream and fudge layer for added crunch.

If I want a more rustic look, I dollop and spread the buttercream instead of piping it.

Storage/Reheating

I store this cake covered in the refrigerator for up to 5 days. The fudge layer sets beautifully and actually tastes better chilled.
To serve leftovers, I let individual slices sit at room temperature for 15–20 minutes—this softens the fudge just enough.
I don’t recommend freezing the entire assembled cake due to the buttercream and icing texture, but the unfrosted cake base can be frozen for up to 2 months.

Related Recipes:

• Butter Cookies
• Maple Fudge
• Decadent Pumpkin Spice Fudge

FAQs

What makes this cake “bumpy”?

The signature look comes from the piped vanilla buttercream ridges under the fudge icing. When the warm fudge is poured on top, it flows around these “bumps,” creating texture and visual interest.

Can I use store-bought frosting instead of making it from scratch?

I prefer homemade frosting for the best flavor, but yes, in a pinch, I’ve used store-bought vanilla frosting and warmed canned chocolate frosting for similar results.

Can I make this cake ahead of time?

Absolutely. I often bake the cake base a day ahead, then add the buttercream and fudge icing the next day before serving. The flavors meld together even better overnight.

Do I need to use a piping bag for the buttercream?

While piping gives the cake its classic bumpy look, I’ve also spooned or spread the buttercream in ridges—it still works, especially if I chill it before pouring the fudge.

Is this cake overly sweet?

Despite having three layers of flavor, I find the sweetness balanced. The cake base isn’t too sugary, and the richness of the fudge icing offsets the sweet buttercream nicely.

Conclusion

Bumpy Chocolate Fudge Cake is more than just dessert—it’s a little piece of nostalgia. With its decadent chocolate base, playful vanilla ridges, and luscious fudge topping, it’s a treat I love making whenever I want to impress a crowd or just indulge in something special. Whether it’s a family gathering or a solo slice with coffee, this cake never disappoints.

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