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Bumpy Cake

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piece of Bumpy Cake on a plate
This bumpy cake is a vintage cake recipe that is full of rich chocolate decadence and ribbons of vanilla buttercream
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Table of Contents
  1. Bumpy Cake Ingredients
  2. How to Make This Bumpy Cake Recipe
  3. How To Serve
  4. Storage
  5. More Recipes You’ll Love
  6. JUMP TO RECIPE

This vintage bumpy cake recipe features rich chocolate cake topped with rows of vanilla buttercream bumps and finished off with a thick layer of chocolate fudge frosting. This beloved midwestern treat, while having an usual name, is as decadent as they come.

piece of Bumpy Cake on a plate

Bumpy Cake Ingredients

Bumpy Cake raw ingredients that are labeled

You’ll need:

For the Chocolate Cake

  • 1 (15.25-ounce) box of dark chocolate fudge cake mix (I used Duncan Hines brand)
  • ¾ cup unflavored brewed coffee, cooled to room temperature
  • ¾ cup whole milk
  • ½ cup vegetable oil
  • ½ cup sour cream
  • 1 teaspoon vanilla extract
  • 4 large eggs, room temperature 

For the Buttercream Filling

  • ¾ cup sweet cream butter, room temperature
  • 1½ teaspoons vanilla extract
  • ¼ teaspoon salt
  • 3 cups powdered sugar, sifted
  • 4 tablespoons heavy cream  

For the Chocolate Frosting

  • 1 cup light brown sugar, lightly packed 
  • ¾ cup unsalted butter, room temperature
  • ⅔ cup buttermilk
  • ½ cup unsweetened cocoa powder
  • ¼ cup light Karo (corn) syrup
  • ½ teaspoon salt
  • 3 cups powdered sugar, sifted
  • 1½ teaspoons vanilla extract

SUBSTITUTIONS AND ADDITIONS

CAKE: I like the richness that the dark chocolate cake mix provides. However, you can substitute a devil’s food, or your favorite chocolate cake mix, if desired. They will all taste great.

How to Make This Bumpy Cake Recipe

For the Chocolate Cake

STEP ONE: Preheat the oven to 350°F. Spray a 9×13-inch metal baking dish with baking spray (Baker’s Joy or a generic version). Set it aside.

OUR RECIPE DEVELOPER SAYS

DO NOT use a glass baking dish for this recipe. Since you will be placing a warm cake into a freezer and then also pouring hot chocolate frosting over a frozen cake, you do not want to risk the glass pan being shocked by the extreme changes in temperatures as this can cause the glass dish to crack and break. 

STEP TWO: Using a medium bowl and a handheld mixer on medium speed, beat together the cake mix, coffee, milk, vegetable oil, sour cream, and vanilla extract. Beat just until combined.

ingredients being blended into the cake mix in a bowl

STEP THREE: Reduce the electric mixer speed to low speed. Add the eggs, one at a time, and beat just until all the eggs are incorporated. Scrape down the sides and bottom of the bowl to ensure that the batter is smooth and well mixed.

egg beaten into the cake mixture in a bowl

STEP FOUR: Pour the cake batter into the prepared pan and bake for 30 minutes, or until a toothpick inserted in the center of the cake comes away clean. Let the cake cool for 30 minutes on the counter, then place the cake into the freezer while you make the buttercream filling.

PRO TIP:

Do not skip chilling the cake. This is important to ensure it is the right temperature for the next layers to set on top.

cake batter poured into a baking dish then baked

For the Buttercream Filling

STEP ONE: Using either a stand mixer or a medium-sized mixing bowl and a handheld mixer on medium-high speed, beat the softened butter, vanilla extract, and salt for 1 to 1½ minutes, until smooth.

butter, vanilla and salt blended in a bowl of heavy cream mixture

STEP TWO: Lower the mixer speed to low and add half the powdered sugar and beat to incorporate. 

powdered sugar blended in a bowl of heavy cream mixture

STEP THREE: Add half the heavy cream, beat for 30 seconds, then add the remaining half of the powdered sugar and heavy cream and beat for an additional 2 to 3 minutes until your buttercream is smooth.

heavy cream beaten in bowl with a blender

STEP FOUR: Using either a decorator’s bag with a large round tip or a gallon-size Ziploc bag with a large corner snipped off, fill the bag with the buttercream. The opening of your piping tip or the size of the hole snipped from the zip-top bag, should be about 1-inch in diameter to get a nice-sized line of buttercream when piped. 

decorators bag filled with frosting

STEP FIVE: Remove the cake from the freezer. Pipe strips of buttercream down the shorter sides of the cake. Space 1 inch apart. Depending on the thickness of the strips, you should be able to pipe 6 strips.

buttercream mixture piped into strips on a cake in a baking dish

STEP SIX: Cover the cake and place it back in the freezer for 1½-2 hours to firm up the buttercream strips.

PRO TIP:

You do not want to skip the freezing of the buttercream step. This will ensure that when pouring the hot chocolate frosting over the buttercream strips that they do not melt. You do need to remember to work quickly though as the chocolate will start to set up quickly when it hits the cold cake and buttercream.

For the Chocolate Frosting

STEP ONE: In a medium saucepan, on medium-high heat, add the light brown sugar, unsalted butter, buttermilk, unsweetened cocoa powder, light Karo syrup, and salt.

brown sugar, butter, buttermilk cocoa, syrup and salt in pot

STEP TWO: Bring the mixture to a boil (this will take about 4 to 5 minutes), making sure to whisk it often so that your frosting doesn’t burn or clump. 

STEP THREE: Once your mixture reaches a rolling boil then you will want to continue to cook it for an additional 3 to 4 minutes or until your chocolate frosting reaches a temperature of 200 to 210°F on a candy thermometer. Your frosting should start getting thick and should be very smooth.

powdered sugar and vanilla whisked into a pot of frosting mixture

STEP FOUR: Turn the heat down to low and add your powdered sugar, one cup at a time, whisking until the frosting is smooth. Once all the powdered sugar has been mixed in, add the vanilla extract and turn off the heat.

STEP FIVE: Transfer your chocolate frosting to a large bowl with a spout to cool slightly. A 4 cup liquid measuring cup works great for this.

STEP SIX: Remove the cake from the freezer. Spoon the slightly cooled chocolate mixture over the top of the cake, paying close attention to covering the buttercream strips. You can use a small spatula to carefully smooth the frosting to evenly cover the bumps and cake. Place the cake into the refrigerator for 15 to 20 minutes to allow the chocolate to set up before slicing and serving.

over head shot of Bumpy Cake in a baking dish

How To Serve

This nostalgic cake is a fantastic treat to make for a birthday party or special occasion, especially for someone who grew up enjoying the original version from their local bakery. Add a scoop of vanilla ice cream on the side for a delightfully indulgent dessert.

For more vintage chocolate desserts, try our crazy cake and mayo cake

Storage

IN THE FRIDGE: Store any leftovers of this sweet treat covered in the refrigerator for up to 7 days. 

IN THE FREEZER: You can freeze this rich and creamy cake for up to 2 months.

close up shot of Bumpy Cake on a baking dish with a piece missing

This moist devil’s food cake is topped with ribbons of vanilla buttercream before fudge frosting is poured on top. It’s an old-fashioned treat that many midwesterners remember from childhood and now you can recreate it at home.

FREQUENTLY ASKED QUESTIONS

Where did the bumpy cake originate?

This delicious cake was originally created by Sanders Confectionary in Detroit, Michigan in the early 1900s and has been a favorite of midwesterners ever since.

Can I freeze the cake once it is complete?

You can freeze this bumpy cake for up to two months.

Do I really need to freeze the cake after the first two steps?

In order for the vanilla buttercream “bumps” to set properly and hold their shape, you do need to make sure you are making time to freeze the cake at the appropriate times indicated.

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piece of Bumpy Cake on a plate

Bumpy Cake

5 from 2 votes
This bumpy cake is a vintage cake recipe that is full of rich chocolate decadence and ribbons of vanilla buttercream
Prep Time 45 minutes
Cook Time 30 minutes
Total Time 3 hours 30 minutes
Servings 12

Ingredients
  

Chocolate Cake

  • 15.25 ounces dark chocolate fudge cake mix (I used Duncan Hines brand)
  • ¾ cup unflavored brewed coffee, cooled to room temperature
  • ¾ cup whole milk
  • ½ cup vegetable oil
  • ½ cup sour cream
  • 1 teaspoon vanilla extract
  • 4 large eggs, room temperature

Buttercream Filling

  • ¾ cup sweet cream butter, room temperature
  • teaspoons vanilla extract
  • ¼ teaspoon salt
  • 3 cups powdered sugar, sifted
  • 4 tablespoons heavy cream

Chocolate Frosting

  • 1 cup light brown sugar, lightly packed
  • ¾ cup unsalted butter, room temperature
  • cup buttermilk
  • ½ cup unsweetened cocoa powder
  • ¼ cup light karo, corn syrup
  • ½ teaspoon salt
  • 3 cups powdered sugar, sifted
  • teaspoons vanilla extract

Instructions
 

Chocolate Cake

  • Preheat the oven to 350°F. Spray a 9×13 metal baking dish with baking spray (Baker’s Joy or a generic version). Set it aside.
  • Using a medium-sized mixing bowl and a handheld mixer on medium speed, beat together the cake mix, coffee, milk, vegetable oil, sour cream and vanilla extract. Beat just until combined.
  • Reduce the mixer speed to low. Add the eggs, one at a time, and beat just until all the eggs are incorporated. Scrape down the sides and bottom of the bowl to ensure that the batter is smooth and well mixed.
  • Pour the cake batter into the prepared baking dish and bake for 30 minutes, or until a toothpick inserted comes away clean. Allow the cake to cool for 30 minutes on the counter then place the cake into the freezer while you make the buttercream filling.

Buttercream Filling

  • Using either a stand mixer, or a medium size mixing bowl and a handheld mixer on medium-high speed, beat the softened butter, vanilla extract, and salt for 1 to 1½ minutes, until smooth.
  • Lower the mixer speed to low and add half the powdered sugar and beat to incorporate.
  • Add half the heavy cream, beat for 30 seconds, then add the remaining half of the powdered sugar and heavy cream and beat for an additional 2 to 3 minutes until your buttercream is smooth.
  • Using either a decorator’s bag with a large round tip, or a gallon-size ziploc baggie with a large corner snipped off, fill the bag with the buttercream. The opening of your piping tip, or the size of the hole snipped from the zip-top bag, should be about 1-inch in diameter to get a nice sized line of buttercream when piped.
  • Remove the cake from the freezer. Pipe strips of buttercream down the shorter sides of the cake. Space 1 inch apart. Depending on the thickness of the strips you should be able to pipe 6 strips.
  • Cover the cake and place back in the freezer for 1½ to 2 hours to firm up the buttercream strips.

Chocolate Frosting

  • In a medium-sized saucepan, on medium-high heat, add the light brown sugar, unsalted butter, buttermilk, unsweetened cocoa powder, light karo syrup and salt.
  • Bring the mixture to a boil (this will take about 4 to 5 minutes), making sure to whisk it often so that your frosting doesn’t burn or clump.
  • Once your mixture reaches a rolling boil, then you will want to continue to cook it for an additional 3 to 4 minutes or until your chocolate frosting reaches a temperature of 200 to 210°F on a candy thermometer. Your frosting should start getting thick and should be very smooth.
  • Turn the heat down to low and add your powdered sugar, one cup at a time, whisking until the frosting is smooth. Once all the powdered sugar has been mixed in, add the vanilla extract and turn off the heat.
  • Transfer your chocolate frosting to a large spouted bowl to slightly cool. A 4 cup liquid measuring cup works great for this.
  • Remove the cake from the freezer. Spoon the slightly cooled chocolate mixture over the top of the cake, paying close attention to covering the buttercream strips. You can use a small spatula to carefully smooth the frosting to evenly cover the bumps and cake. Place the cake into the refrigerator for 15 to 20 minutes to allow the chocolate to set-up before slicing and serving.

Notes

  • DO NOT use a glass baking dish for this recipe. Since you will be placing a warm cake into a freezer and then also pouring hot chocolate frosting over a frozen cake, you do not want to risk the glass pan being shocked by the extreme changes in temperatures as this can cause the glass dish to crack and break.
  • Do not skip chilling the cake. This is important to ensure it is the right temperature for the next layers to set on top.
  • You do not want to skip the freezing of the buttercream step. This will ensure that when pouring the hot chocolate frosting over the buttercream strips that they do not melt. You do need to remember to work quickly though as the chocolate will start to set up quickly when it hits the cold cake and buttercream.

Nutrition

Calories: 742kcal | Carbohydrates: 110g | Protein: 6g | Fat: 33g | Saturated Fat: 19g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 9g | Trans Fat: 1g | Cholesterol: 138mg | Sodium: 422mg | Potassium: 279mg | Fiber: 2g | Sugar: 97g | Vitamin A: 980IU | Vitamin C: 1mg | Calcium: 103mg | Iron: 1mg
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  1. Nancy says

    5 stars
    Instead of buttercream strips, I would like to spread it, then follow with the chocolate. Is the buttercream recipe enough to frost the entire cake?