This nostalgic Bumpy Cake is a cherished Midwest dessert featuring a rich chocolate cake base, piped rows of thick vanilla buttercream “bumps,” and a smooth layer of glossy chocolate ganache. A true retro classic that brings back sweet memories with every bite.

Why You’ll Love This Recipe

Bumpy Cake is more than a dessert—it’s a slice of Midwestern history. The combination of moist chocolate cake, creamy vanilla buttercream, and silky ganache creates a unique texture and flavor contrast that’s both nostalgic and indulgent. Whether you remember it from your childhood or are discovering it for the first time, this cake is perfect for birthdays, holidays, and special gatherings. Plus, it’s fun to make and even more enjoyable to serve.

Ingredients

(Tip: You can find the complete list of ingredients and their measurements in the recipe card below.)

For the Cake:

1 cup granulated sugar
½ cup brown sugar
¾ cup unsweetened cocoa powder
1 ½ teaspoons baking powder
1 ½ teaspoons baking soda
½ teaspoon salt
2 large eggs
1 cup buttermilk
½ cup vegetable oil
2 teaspoons vanilla extract
1 cup boiling water
1 ¾ cups all-purpose flour

For the Buttercream “Bumps”:

½ cup unsalted butter, softened
2 cups powdered sugar
2 tablespoons heavy cream
1 teaspoon vanilla extract
Pinch of salt

For the Chocolate Ganache:

1 cup heavy cream
8 ounces semi-sweet chocolate chips
1 tablespoon corn syrup (optional, for added shine)

Directions

Preheat oven to 350°F (175°C). Grease and line a 9×13 inch baking pan with parchment paper.
In a large bowl, whisk together flour, cocoa powder, granulated sugar, brown sugar, baking powder, baking soda, and salt.
Add eggs, buttermilk, oil, and vanilla extract. Mix until combined. Slowly add the boiling water and whisk until smooth. The batter will be thin.
Pour into the prepared pan and bake for 30–35 minutes, or until a toothpick inserted in the center comes out clean. Allow the cake to cool completely in the pan.
To prepare the buttercream, beat the softened butter until fluffy. Add the powdered sugar, heavy cream, vanilla extract, and salt. Beat until light, smooth, and pipeable.
Transfer the buttercream into a piping bag fitted with a round tip. Pipe 4–5 thick, straight rows of buttercream across the cooled cake. Freeze the cake for 15–20 minutes to firm up the buttercream.
For the ganache, heat the heavy cream just until simmering. Pour over chocolate chips in a heatproof bowl. Let sit for 2 minutes, then stir until completely smooth. Stir in corn syrup, if using, for extra shine.
Pour the ganache gently over the chilled cake, spreading carefully to cover the buttercream bumps without flattening them.
Refrigerate until ganache is set. Slice and serve chilled or at room temperature.

Servings and timing

Servings: 12 servings
Prep Time: 30 minutes
Cooking Time: 35 minutes
Total Time: 1 hour 5 minutes
Calories per serving: 420 kcal

Variations

Chocolate buttercream: Use chocolate buttercream instead of vanilla for a double chocolate twist.
Sheet cake style: Bake in a sheet pan for a thinner, snack-style version.
Nutty addition: Add chopped walnuts or pecans to the batter for crunch.
Coffee kick: Replace some of the boiling water with strong brewed coffee to enhance the chocolate flavor.
Mini cakes: Bake in mini loaf pans or cupcake tins and pipe buttercream bumps accordingly.

Storage/Reheating

Storage: Store in an airtight container in the refrigerator for up to 4 days.
Freezing: Freeze individual slices or the whole cake (without ganache) wrapped tightly for up to 2 months. Thaw in the fridge and finish with ganache before serving.
Reheating: Best served cold or at room temperature. Do not microwave.

FAQs

What is Bumpy Cake?

Bumpy Cake is a traditional Midwest dessert made of chocolate cake topped with piped vanilla buttercream and coated in chocolate ganache.

Why is it called Bumpy Cake?

The “bumps” are rows of buttercream frosting piped across the cake before the ganache is poured over them, creating a distinctive bumpy surface.

Can I make this cake ahead of time?

Yes. Bumpy Cake actually tastes better the next day after chilling and allowing the flavors to meld.

Can I use a boxed cake mix?

You can use a chocolate cake mix in place of the homemade base, but the homemade version adds depth and moisture that’s hard to beat.

Is the ganache supposed to be thick?

Yes, but it should be pourable. If too thick, warm gently or add a bit more cream.

Can I use milk instead of cream in the ganache?

Heavy cream is best for smooth texture, but you can use full-fat milk in a pinch with a slightly thinner result.

How do I get smooth buttercream bumps?

Pipe with a steady hand and chill them before adding ganache to maintain their shape.

Can I make this gluten-free?

Yes, substitute with a 1:1 gluten-free flour blend, though texture may vary slightly.

Should I serve it cold or room temp?

It’s traditionally served cold, but it’s delicious at room temperature as well.

What’s the best chocolate for ganache?

High-quality semi-sweet chocolate chips or chopped bars give the best flavor and consistency.

Conclusion

Bumpy Cake is a slice of Midwest comfort and charm—a perfect balance of rich chocolate cake, creamy vanilla frosting, and glossy ganache. With its signature bumps and nostalgic flavor, it’s a conversation-starting dessert that’s as fun to make as it is to eat. Whether you’re bringing back a childhood favorite or sharing it for the first time, Bumpy Cake is a timeless treat that’s always in style.

Bumpy Cake

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This classic Bumpy Cake is a nostalgic Midwest dessert featuring moist chocolate cake topped with thick vanilla buttercream bumps and a smooth, glossy layer of chocolate ganache. It’s a rich and whimsical treat perfect for birthdays, gatherings, or chocolate lovers.

Author: Mari
Prep Time: 30 minutes
Cook Time: 35 minutes
Total Time: 1 hour 5 minutes
Yield: 12 servings 1x
Category: Dessert
Method: Baking
Cuisine: American
Diet: Vegetarian

Instructions

Preheat oven to 350°F (175°C). Grease and line a 9×13-inch baking pan with parchment paper.
In a large mixing bowl, whisk together flour, cocoa powder, granulated sugar, brown sugar, baking powder, baking soda, and salt.
Add eggs, buttermilk, vegetable oil, and vanilla extract. Mix until combined.
Gradually stir in the boiling water until batter is smooth. Batter will be thin.
Pour batter into the prepared pan and bake for 30–35 minutes, or until a toothpick inserted into the center comes out clean. Let cake cool completely in the pan.
While the cake cools, prepare the buttercream. Beat softened butter until light and fluffy. Add powdered sugar, heavy cream, vanilla, and salt. Beat until smooth and thick.
Transfer buttercream to a piping bag fitted with a large round tip. Pipe thick, evenly spaced rows (bumps) across the top of the cooled cake.
Place the cake in the freezer for 15–20 minutes to firm up the buttercream.
For the ganache, heat the heavy cream just to a simmer. Pour over the chocolate chips in a bowl and let sit for 2 minutes. Stir until smooth and glossy. Stir in corn syrup if using.
Pour ganache evenly over the cake, making sure to coat the buttercream bumps gently. Chill until ganache is set before slicing and serving.

Notes

For neater slices, chill the cake fully before cutting.
Corn syrup in the ganache is optional but enhances the glossy finish.
Use a serrated knife or a warm knife for clean cuts through the ganache and buttercream layers.
This cake stores well in the refrigerator for up to 4 days.

Nutrition

Serving Size: 1 slice
Calories: 420
Sugar: 35g
Sodium: 220mg
Fat: 26g
Saturated Fat: 14g
Unsaturated Fat: 10g
Trans Fat: 0g
Carbohydrates: 45g
Fiber: 2g
Protein: 4g
Cholesterol: 75mg