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A slice of bumpy cake made with chocolate cake and vanilla buttercream frosting with fudge icing poured on top sitting on a white plate.
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5 from 1 vote

Bumpy Cake

Bumpy Cake is delicious recipe is made with a rich, moist chocolate devil's food cake that is covered in ribbons of vanilla buttercream and poured fudge frosting for the traditional "bumpy" look! It is a Michigan favorite that got its start in Detroit at Sanders Confectionary Company but is easy to make at home.
Prep Time20 mins
Cook Time40 mins
Chilling Time45 mins
Total Time1 hr 45 mins
Course: Dessert
Cuisine: American
Servings: 15 servings
Calories: 667kcal
Author: Amy Nash



  • 2 cups all-purpose flour, spooned & leveled (250g)
  • ¾ cup unsweetened cocoa powder (100g)
  • 2 teaspoons baking soda
  • 1 teaspoon baking powder
  • 1 teaspoon salt
  • 1 ¾ cups granulated sugar (350g)
  • 1 cup buttermilk, room temperature (244g)
  • ½ cup oil (100g)
  • 2 large eggs, room temperature
  • 2 teaspoons vanilla extract
  • 1 cup very hot water

Buttercream Frosting

  • ¼ cup salted butter, softened
  • ¼ cup shortening
  • 2 ½ cups powdered sugar (300g)
  • 1 teaspoon vanilla extract
  • Pinch of salt
  • 4 Tablespoons heavy cream or milk

Fudge Icing

  • 1 cup granulated sugar (200g)
  • ½ cup buttermilk
  • cup corn syrup
  • cup unsweetened cocoa powder (35g)
  • Pinch of salt
  • 1 cup salted butter, cubed (divided)
  • 2 ½ cups powdered sugar (300g)
  • 2 teaspoons vanilla extract



  • Preheat oven to 350°F. Spray a 9x13-inch pan with baking spray.
  • Whisk the flour, cocoa powder, baking soda, baking powder, and salt together in a bowl. Combine the sugar, buttermilk, oil, eggs, and vanilla in another large bowl. Add the dry ingredients to the wet ingredients gradually, stopping to scrape the bottom and sides of the bowl. Mix in the hot water. The batter will be very thin.
  • Pour the chocolate cake batter into the prepared pan and bake for 30 to 35 minutes. Check the cake with a toothpick to see if it comes out clean to know when it is done. Cool completely.

Buttercream Frosting

  • Beat the butter and shortening for 2-3 minutes until creamy and smooth. Gradually add the powdered sugar, 1 cup at a time, while mixing on low speed until combined. Add the vanilla, salt, and cream, then beat on medium-high speed until light and fluffy, about 2-3 minutes.
  • Transfer the frosting to a piping bag fitted with a large open circle tip. Or transfer it to a heavy duty Ziploc bag and snip off one corner.
  • Pipe 4 thick strips of frosting evenly down the length of the cake to create the logs or "bumps". You shouldn't have much, if any, frosting leftover. Stick the cake in the freezer while preparing the fudge icing.

Fudge Frosting

  • In a medium saucepan, heat the sugar, buttermilk, corn syrup, cocoa powder, salt, and half of the butter over medium-low heat until it comes to a boil. Continue to cook, stirring frequently, until it reaches 235°F on a candy thermometer clipped to the side of the pan.
  • Remove from the heat and add the remaining cubed butter. Stir until melted, then whisk in the powdered sugar and vanilla extract.
  • Pour the fudge frosting evenly over the chilled cake, covering the buttercream logs and making sure to cover the top as much as possible. Refrigerate for 30 minutes or stick in the freezer for 15 minutes to set up before slicing and serving.


  • Storage: This cake keeps well in covered with plastic wrap or in an airtight container at room temperature for 4-5 days.
  • Freezing: You can freeze leftovers for 2-3 months. Thaw at room temperature before serving.


Calories: 667kcal | Carbohydrates: 100g | Protein: 5g | Fat: 30g | Saturated Fat: 13g | Polyunsaturated Fat: 4g | Monounsaturated Fat: 11g | Trans Fat: 1g | Cholesterol: 71mg | Sodium: 508mg | Potassium: 164mg | Fiber: 3g | Sugar: 83g | Vitamin A: 603IU | Vitamin C: 1mg | Calcium: 67mg | Iron: 2mg