Bumpy Cake is a chocolate cake topped with ribbons of vanilla buttercream and covered in chocolate ganache. The cake gets its name from the “bumps” created by the frosting when spread on top of the cake.
This recipe is in partnership with Imperial Sugar. CLICK HERE for the full recipe!

Bumpy Cake
Bumpy cake is a classic dessert that has its origins in Detroit, Michigan. It’s a rich Devil’s Food cake topped with a rich, buttery vanilla frosting and covered in a thick layer of chocolate ganache. The cake gets its name from the “bumps” created by the frosting when spread on top of the cake.
Bumpy Cake was created by the Sanders Candy Company, known for their delicious chocolates and desserts. Rumor has it that company founder Fred Sanders ran out of vanilla frosting one day, so he spritzed on what he had and poured chocolate ganache on top to cover the cake, creating the bumps you see. The cake was a hit and is still being sold to this day! I don’t know if that’s true, but it’s a good story!
Special tools you may need
Aside from the obvious, a 9×13, a stand mixer, etc., there are a few tools that will make the process easier!
- A piping bag. And if you have a big round piping tip, even better! But just one bag will do, because you can cut off the end of the bag, creating a round opening. If you don’t have piping bags, you can do this with a zip-top bag too!
- An offset spatula. This isn’t strictly necessary, but it always makes it easier to spread the chocolate fudge frosting. If you don’t have one, I highly recommend getting one.
- A whisk. This isn’t really “special” but it really helps make that chocolate ganache you pour on top of it smooth!

Ingredients:
For the full recipe and ingredient list, CLICK HERE!
Cake:
- all purpose flour
- granulated sugar
- Unsweetened cocoa powder
- baking powder
- baking powder
- eggs
- buttermilk
- rapeseed oil
- vanilla extract
- Brewed coffee
Vanilla Frosting:
- butter
- powdered sugar
- milk
- vanilla extract
Chocolateglaze:
- butter
- Dutch cocoa powder
- Fat whipped cream
- Light corn syrup
- Sifted powdered sugar

How to make this bumpy cake recipe:
- Cake: Preheat the oven to 350°F. Coat a 9×13-inch baking pan with nonstick spray and set aside.
- In the bowl of your stand mixer fitted with the paddle attachment, combine the flour, sugar, cocoa powder, baking powder, baking soda and salt. Blend on low speed until combined.
- With mixer still on low, add eggs, buttermilk, oil, and vanilla and mix until well combined, scraping sides of bowl as needed. Slowly pour in the coffee and mix until smooth and combined.
- Pour the cake batter into the prepared pan and bake for 25 – 30 minutes, until the center is set and a toothpick inserted in the center comes out clean.
- Place the cake tin on a wire rack and let cool completely. Using a serrated knife, level the top of the cake if it curves as it bakes so the top is flat.
- Vanilla Frosting: In the bowl of your stand mixer fitted with the paddle attachment, mix the butter on medium speed until smooth. Add the powdered sugar and 1 tablespoon milk and continue beating for 2 minutes until creamy, scraping down the sides of the bowl as needed and adding more milk if the glaze is too thick.
- Place the icing in a piping bag fitted with a 1-inch bullet tip, or simply snip off the bottom of the bag with scissors. Pipe the frosting in long tubes, about 1 inch (2.5 cm) apart, across the cake. Place the cake in the freezer while you prepare the chocolate icing.

- Chocolateglaze: In a medium saucepan over medium-high heat, melt butter, cocoa powder, heavy cream, and corn syrup. Bring the mixture to a boil and cook for 2 minutes, stirring constantly. Slowly add the powdered sugar and continue beating until combined. Continue cooking and beating 4 – 5 minutes until mixture is smooth and shiny. Take off the heat.

- Transfer the glaze to a glass bowl and let cool, stirring frequently, until warm but not hot, 10 – 15 minutes.
- Remove the cake from the freezer and pour the chocolate frosting on top, coating the vanilla frosting first and then carefully filling in the rest of the top of the cake, gently spreading if necessary, being careful not to disturb the vanilla frosting . Allow all of the chocolate icing to set before serving.

Tips for success:
- Use good quality cocoa powder: The chocolate flavor is the star of bumpy cake, so it’s important to use a high-quality cocoa powder for the best flavor. I recommend using Dutch processed cocoa powder or even Hershey dark cocoa powder.
- Make sure the cake is completely cool before adding the vanilla frosting: if the cake is still warm, the frosting will melt and lose the round frosting tubes you want to use to create the peaks. Chilling the cake before adding the ganache will ensure the buttercream knobs will hold their shape as you spread them over the warm chocolate frosting. And since the cake is also chilled, the chocolate will rise faster.
- Use a warm knife to cut the cake: this will help get clean slices and prevent the cake from forming. You don’t have to do this, but a knife run under hot water cuts through more easily. Simply dry off the water and wipe away between each slice.

Does Bumpy Cake need to be refrigerated?
Bumpy cake is traditionally served chilled. You absolutely do not have to refrigerate it, but it is recommended for authenticity. I don’t actually prefer a chilled cake so I keep mine at room temperature and it’s perfectly fine, but that’s just me!
Click HERE for the FULL RECIPE
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