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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.
The iconic "bumpy cake" is a Motor City classic that has its roots in a Detroit chocolate shop that opened in 1875. Their signature cake style didn't come about until the early 1900's, but it took off and was hugely popular in Michigan. Of course I had to include it in my collection of Michigan-inspired recipes in my American Eats series where I visit popular and iconic foods from each state, one state at a time.
This copycat bumpy cake is my homemade version of the classic, and it is goooooood. My chocolate-loving husband was obsessed with this one and I'm ready to make it again soon because of it's unique texture and flavor combo.
Why this Recipe Works
- It's a simple, straightforward chocolate devil's food cake that I have made countless times over the years and requires no advance baking skills. The trick is to use really hot water to "bloom" the cocoa powder, which increases the depth of the chocolate flavor.
- The poured fudge frosting sets up like, well, fudge for a fantastically rich and unique texture and flavor.
- No special decorating skills are needed beyond the ability to pipe a (moderately) straight line of frosting.
How to Make This Recipe
Start by whisking the dry ingredients together in a large bowl so that the cocoa powder and leavening agents are evenly dispersed.
In a separate bowl, combine the wet ingredients like the sugar, buttermilk, oil, eggs, and vanilla. I used my stand mixer, but a hand mixer will work just as well and you could even make this cake by hand just using a whisk.
Gradually add the flour and cocoa powder mixture, stirring to combine and stopping to scrape the bottom and sides of the bowl.
Add in the hot water (this makes a very thin batter), mixing until everything is combined. Pour into a 9x13-inch pan that has been sprayed with baking spray and bake for 30-35 minutes until a toothpick inserted into the center of the cake comes out clean or with just a few crumbs on it.
Let the cake cool completely, then stick it in the freezer while working on the buttercream frosting.
The make the vanilla buttercream, combine the butter and shortening in a large bowl and mix well until smooth. Add the powdered sugar gradually, followed by the heavy cream, vanilla, and pinch of salt. Beat for 2-3 minutes until light.
Transfer the frosting to a piping bag fitted with a large open round tip and pipe four thick ribbons (or bumps or logs, whatever you want to call them) on top of the cooled cake. You should use up pretty much all of the frosting. Stick the cake back in the freezer while you make the fudge frosting.
To make the fudge frosting, combine the sugar, buttermilk, corn syrup, cocoa powder, salt, and half of the butter in a medium saucepan (save the rest of the butter for later). Heat over medium-high heat until the mixture comes to a boil, stirring frequently. Continue to cook until the mixture reaches 235°F on a candy thermometer clipped to the side of the pan.
Add in the reserved cubed butter to the hot fudge mixture and stir until it is completely melted, then whisk in the powdered sugar and vanilla extract until smooth.
Pour the fudge frosting evenly over the chilled cake while the frosting is still hot. If it is too thick or cools down too much, either warm it slightly or add a tablespoon or two of hot water.
You can certainly replace the hot water with an equal amount of hot coffee in this cake recipe. Some people swear by it, saying it improves the chocolate flavor for them. Personally, I don't think it does much and we aren't coffee drinkers so I never have it on hand anyway, but go for it if you want to give it a try!
I mean, it's your own kitchen, so don't let me tell you want to do, but if you pour hot icing over soft buttercream, chances are you are going to have it melt more than if you take the time to freeze those frosting bumps first.
- Storage: Bumpy cake will be good stored at room temperature for 4-5 days as long as it is covered with plastic wrap or is in an airtight container. But you can also keep it in the fridge. Just let it come to room temperature before enjoying or the cake might taste dry.
- Freezing: You can freeze your finished bumpy cake for 2-3 months. Just be sure to protect it well with plastic wrap.
- Other flavors: You might find that you like this type of cake so much that you want to try swapping out the chocolate for another flavor. Go right ahead! In fact, the Sanders Confectionary Company has four flavors of this style of cake including vanilla, carrot, and caramel in their line up with the classic chocolate fudge! But I think a peanut butter base with the chocolate frosting would be amazing. Or maybe my banana bars with penuche icing, just cooked in a 9x13 pan!
More Chocolate Recipes
- Chocolate Cream Pie
- Copycat Levain Bakery Dark Chocolate Peanut Butter Chip Cookies
- Homemade Nutella Brownies
- Best Chocolate Cupcakes
- 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
- 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
- 1 cup granulated sugar (200g)
- ½ cup buttermilk
- ⅓ cup corn syrup
- ⅓ 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.
- 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.
- 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.
More States I Have Visited in my American Eats Series
Alabama • Alaska • Arizona • Arkansas • California • Colorado • Connecticut • Delaware • Florida • Georgia • Hawaii • Idaho • Illinois • Indiana • Iowa • Kansas • Kentucky • Louisiana • Maine • Maryland • Massachusetts • Montana • New York • Oregon • Puerto Rico • South Carolina • South Dakota • Texas • Utah • Wisconsin