Bumpy Cake (Chocolate Cake with Vanilla Buttercream and Chocolate Fudge) Recipe

This moist, dark chocolate cake is topped with generous "bumps" of vanilla buttercream and covered with a fudgy chocolate frosting.

A slice of bumpy cake served on a small white plate. The bumps of vanilla buttercream are visible.

Serious Eats / Alexandra Penfold

Why This Recipe Works

  • Freezing the cake before piping the buttercream and then freezing the piped cake before pouring the frosting on chills the buttercream enough for the frosting to properly adhere and cover the "bumps."

In my quest to capture American desserts, I've polled friends and relatives for favorites from their childhoods. Among Michiganders, especially those with Detroit roots, Sanders' Bumpy Cake commands some serious nostalgia points. What is Bumpy Cake? Short answer: delectable. Long answer: a Devil's Food Cake with stripes of sugary buttercream topped with "pourable fudge" frosting. Yes, pourable fudge frosting.

This recipe has been in the works since January. The first step was a little recon to uncover the bumpy history behind this regional treat. The Sanders Confectionery was founded by Fred Sanders in Detroit in 1875. What began as a candy company expanded overtime to include ice cream and soda fountain treats as well as baked goods. One hundred years and three generations later, they had 58 shops in the metro Detroit area.

Serious Eater CityMinx shared this description from her cousin who grew up in Detroit in the 60s:

Sanders was a counter style luncheonette (there are only a few left) who made the best hot fudge cream puffs... Our treat was to go there and have a tuna sandwich and then a yummy cream puff. They still sell the hot fudge everywhere and I happen to have a jar in my fridge.
The bumpy cake was a chocolate cake (genoise-like, not too light and not too dense) that had big straight pipings of a whipped white buttercream frosting from end to end of the cake. The cake was then coated in a ganache-like fudge icing. You didn't see the white buttercream since it was covered. The surprise was when you cut into it and found out what the "bumps" were!

For Detroit folk, Bumpy Cakes were the stuff of celebrations. Another friend told me, "If you ever went to a baby shower or your grandma's house, there was often a bumpy cake." Alas, the original Sanders lives on only in memory. Sanders was purchased in 2002 by Morley Candy, another Michigan-based candy company. Morley has been revitalizing the brand, putting Bumpy Cakes back in circulation, and now you can get Bumpy Cakes shipped to you anywhere in the country. Naturally I needed to order one to taste the real deal for myself.

Fortunately you can make a really good facsimile of Sanders' cake at home. How good? I don't want to brag, so I'll let my Michigan-born co-worker do the talking for me:

Wow, Alexandra, the first bite of your cake, and the aroma, it took me back to when I was about 4 years old and we lived in Detroit (within reasonable driving distance to a Sanders Bakery). I definitely did have that cake when I was little, probably a special treat at my grandparents' place. This Detroit native would say you hit the mark with your bumpy cake! Thanks for the scrumptious treat and peeling the years away for a few happy mouthfuls!

So there you have it. What you have before you is a moist dark chocolate cake topped with sweet, sweet buttercream and a fudgy, almost caramel-y chocolate frosting. Though there are three separate components that require freezer cooling to obtain picture perfect results, this cake is well worth the effort. Happy mouthfuls, indeed.

This recipe is adapted from a Sanders' recipe published some years ago in a Detroit newspaper and accessed via Food.com.

May 2012

Recipe Details

Bumpy Cake (Chocolate Cake with Vanilla Buttercream and Chocolate Fudge) Recipe

Active 90 mins
Total 3 hrs 15 mins
Serves 12 servings

This moist, dark chocolate cake is topped with generous "bumps" of vanilla buttercream and covered with a fudgy chocolate frosting.


For the Cake:

  • 1 tablespoon unsalted butter

  • 1/2 cup plus 2 tablespoons unsweetened Dutch process cocoa powder

  • 1/2 cup hot black coffee

  • 1/2 cup canola oil

  • 1 cup buttermilk

  • 1 tablespoon pure vanilla extract

  • 1 1/2 teaspoons baking soda

  • 1/2 teaspoon salt

  • 2 large eggs, lightly beaten

  • 3/4 cup dark brown sugar, firmly packed

  • 3/4 cup white sugar

  • 2 cups all-purpose flour

For the Buttercream Frosting:

  • 1/4 cup unsalted butter

  • 1/4 cup vegetable shortening

  • 2 1/2 cups confectioners' sugar

  • 1 teaspoon vanilla extract

For the Pourable Fudge Frosting:

  • 1/2 cup buttermilk, room temperature

  • 2 1/2 cups powdered sugar

  • 1 teaspoon vanilla extract

  • 1 cup sugar

  • 1/3 cup unsweetened Dutch process cocoa powder

  • 1/3 cup dark corn syrup

  • 1/4 teaspoon salt

  • 16 tablespoons (2 sticks) unsalted butter, cut into tablespoon-sized pieces


  1. Set oven rack to the middle position and preheat oven to 375°F (190°C). Grease a 9- by 13-inch pan or baking dish with butter. Add 2 tablespoons cocoa powder to pan and shake and tap pan gently until the butter is completely coated in cocoa. Tip out excess.

  2. In the bowl of a stand mixer, combine cocoa and coffee, beat on medium speed for 30 seconds. Add oil, beat for 30 seconds; add buttermilk, beat for 30 seconds; add baking soda, beat for 30 seconds; add salt, beat for 30 seconds; add vanilla, beat for 30 seconds; add eggs, beat for 30 seconds; add sugars, beat for 30 seconds. Add flour and beat about 5 minutes to remove any lumps. Batter may begin to bubble.

  3. Pour batter into prepared pan and use spatula to smooth top. Bake until cake tester comes out clean, 35 to 40 minutes. Transfer to a rack and allow to cool for at least 30 minutes. Transfer to the freezer for at least an hour and up to overnight.

  4. For the Buttercream: In the bowl of a stand mixer fitted with a paddle attachment, cream together butter and shortening on medium speed until light and fluffy, about 3 minutes. Add confectioners’ sugar and mix to fully incorporate, about 1 minute. Add vanilla extract and mix until blended, about 30 seconds. Transfer frosting to a piping bag fitted with a large round tip. Refrigerate for at least 15 minutes to firm up frosting.

  5. Pipe frosting crosswise into seven 1-inch wide lines spaced 1-inch apart (each "bump" should run the length of the cake, 9-inches long). Return cake to the freezer for at least 30 minutes to set the frosting.

    Vanilla buttercream piped into "bumps" on the chocolate cake.

    Serious Eats / Alexandra Penfold

  6. For the Fudge: In a large bowl whisk together buttermilk, confectioner's sugar and vanilla and set aside. In a medium saucepan, combine, sugar, cocoa, corn syrup, salt and 1 stick worth of butter. Stir occasionally to fully incorporate butter as it's melting then bring mixture to a boil over medium high heat.

  7. Cook until mixture registers 240°F (116°C) on a candy or instant-read thermometer (a small amount dropped into cold water should form a soft, malleable ball), then remove from heat. While whisking constantly, add hot mixture to buttermilk mixture. Add remaining butter pieces and continue whisking until fully incorporated and mixture has cooled (frosting must be only slightly warm).

    The cocoa-corn syrup mixture is boiled in a small saucepan affixed with a candy thermometer.

    Serious Eats / Alexandra Penfold

  8. Remove frosted cake from freezer and pour cooled frosting over the cake in long strokes to cover buttercream rolls completely. Note: frosting will be thin and saucelike. Working quickly and evenly you'll be able to completely cover the bumps with a thin layer of frosting, while "frosting runoff" will create fudgy pockets along the surface beside the bumps that will firm up in the freezer. Return cake to freezer for at least 30 minutes more to set. A smaller, paring knife is most effective for cutting while maintaining the cake's unique look. Serve chilled and store leftovers in refrigerator or freezer.

Special Equipment

9- by 13-inch baking dish or pan, stand mixer, piping bag and large round piping tip, candy thermometer

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Nutrition Facts (per serving)
788 Calories
35g Fat
115g Carbs
6g Protein
Show Full Nutrition Label Hide Full Nutrition Label
Nutrition Facts
Servings: 12
Amount per serving
Calories 788
% Daily Value*
Total Fat 35g 45%
Saturated Fat 15g 77%
Cholesterol 88mg 29%
Sodium 381mg 17%
Total Carbohydrate 115g 42%
Dietary Fiber 2g 7%
Total Sugars 94g
Protein 6g
Vitamin C 0mg 2%
Calcium 62mg 5%
Iron 4mg 20%
Potassium 114mg 2%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
(Nutrition information is calculated using an ingredient database and should be considered an estimate.)