🍫 Detroit Bumpy Cake

A Beloved Michigan Classic

Few desserts are as closely tied to Detroit tradition as Bumpy Cake. Known for its distinctive ridges of buttercream tucked beneath a smooth layer of rich chocolate icing, this iconic treat has been a favorite at family celebrations, bake sales, and holiday gatherings for generations.

What makes it special is the contrast of textures and flavors. A moist chocolate cake forms the base, while strips of creamy buttercream add sweetness and character. The finishing touch is a silky fudge icing that settles over the buttercream, creating the cake’s famous “bumps” and signature appearance.

Whether you’re sharing it at a birthday party or bringing it to a potluck, this nostalgic dessert is always a crowd-pleaser.

Ingredients

Cake

Ingredient	Amount
Devil’s food cake mix	1 box
Eggs, oil, and water	As directed on package

Buttercream Filling

Ingredient	Amount
Butter, softened	4 tablespoons
Powdered sugar	1½ cups
Vanilla extract	½ teaspoon
Milk	1 tablespoon
Salt	Pinch

Fudge Icing

Ingredient	Amount
Buttermilk	½ cup
Corn syrup	2 tablespoons
Butter	½ cup
Unsweetened cocoa powder	⅔ cup
Powdered sugar	3½ cups
Salt	Pinch
Vanilla extract	½ teaspoon

Instructions

Step 1: Bake the Cake

Preheat the oven to 350°F (175°C). Grease a 9×13-inch baking pan.

Prepare the cake mix according to the package directions. Pour the batter into the prepared pan and bake as directed. Allow the cake to cool completely before continuing.

Step 2: Prepare the Buttercream

In a mixing bowl, beat the butter until smooth and creamy.

Add the powdered sugar, milk, vanilla, and salt. Continue mixing until light and spreadable.

Refrigerate for about 15 minutes to firm slightly.

Transfer the buttercream to a piping bag or plastic bag with a corner snipped off. Pipe evenly spaced lines across the surface of the cooled cake, leaving about 1 inch between each row.

Place the cake in the freezer while preparing the icing.

Step 3: Make the Chocolate Icing

In a saucepan over medium heat, combine the buttermilk, corn syrup, butter, cocoa powder, and salt.

Bring the mixture to a gentle simmer, stirring frequently, and cook for about 3 minutes.

Remove from the heat and gradually whisk in the powdered sugar until smooth. Stir in the vanilla extract.

Allow the icing to cool for approximately 10 minutes.

Step 4: Assemble the Cake

Remove the cake from the freezer.

Slowly pour the chocolate icing over the buttercream rows, covering the entire surface. The icing will settle around the buttercream, creating the cake’s signature appearance.

Refrigerate for at least 30 minutes, or until the icing is fully set.

Serving Suggestions

• Cut into squares for easy serving.
• Serve chilled for the classic texture and flavor.
• Store leftovers in the refrigerator.
• Perfect for birthdays, family gatherings, potlucks, and holiday dessert tables.

Rich chocolate, creamy buttercream, and a touch of nostalgia make this Detroit favorite a dessert worth sharing.