Tunnel of Fudge Cake

This updated version of the Tunnel of Fudge Cake is take on the classic nostalgic vintage cake that popularized the bundt pan. It features a creamy dark chocolate filling with nuts and cacao nibs!

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Lately I’ve been obsessed over nostalgic American vintage recipes like my version of the black bottom cupcakes and secret ingredient peanut butter blossoms. Next on my list was the classic Tunnel of Fudge cake that won Ella Helfrich second place in the 1966 Pillsbury Bake Off. What’s remarkable is that it not only came in second place (the first-place winner, Mari Petrelli’s Golden Gate Snack Bread is largely a footnote in the Bake Off history) but that it popularized Nordic Ware’s bundt pan (<- affiliate link).

Nordic Ware started out in 1950 making bundt pans, but sales were slow until the Tunnel of Fudge cake recipe exploded in popularity. Soon, Nordic Ware had to run their factory 24/7 to keep up with demands of their pan, cranking out 30,000 pans per day during the peak period. And once Pillsbury discontinued the key ingredient, Double Dutch Frosting Mix, bakers around the US complained so much that Pillsbury, brought back the mix temporarily, then eventually permanently discontinued it, finally posting a recipe for the cake that could be made without the frosting mix. Variations of the recipe have popped up here and there but the version that I ended up adapting was developed by Shirley Corriher, author of Bakewise (<-affiliate link), an excellent book that dives into the science of baking.

What is the Tunnel of Fudge Cake?

The Tunnel of Fudge cake is a cake that was initial created by Ella Helfrich for the 1966 Pillsbury Bake Off contest. It won 2^nd place and created a huge demand for the Bundt pan. The initial recipe used a powdered frosting mix which was discontinued in the mid-80s. The cake itself is a bundt cake that has a fudgy center, where the batter is slightly underbaked. Like a bundt pan version of the individual molten lava cake, the bundt cake is intensely chocolatey, and rich, with added nuts to give it texture and flavor.

How this recipe is adapted

The original recipe used a powdered frosting mix that was discontinued. Though you can find similar powdered frosting mixes to replicate the original recipe, Pillsbury published a version of the cake that you can make without this mix. 

Food scientist and recipe developer Shirley Corriher built her version of the Tunnel of Fudge recipe from the ground up, creating a more reliable version of the cake. My version is adapted from Corriher’s version, from her book Bakewise. I did minor tweaks to the recipe, swapping out some of the nuts for roasted cacao nibs to amplify the chocolate flavor. I also added a little bit of espresso powder, again to amplify this chocolate flavor. Finally, I shifted the bake temperature so the oven is preheated to 400°F when you place the pan in, lowering the temperature to the more traditional 350°F after you place the cake in the oven. This initially hotter oven temperature helps sets the cake on the outside, ensuring that the outer part of the cake bakes and sets, while the inside stays moist and fudgy.

Is it safe to eat the undercooked center cake batter?

The more fudgy center of the cake is due to the cooked outer rim of the cake and the underdone center of the cake. The biggest concern some folks have is eating undercooked cake batter. The more concerning pathogen in undercooked cake batter is raw egg and flour. Both can harbor salmonella or E coli bacteria or other food borne pathogens. E. coli is killed at 160°F, salmonella is killed at 165°F. As long as the internal temperature of the cake reaches 165°F, there’s no chance of getting sick from the cake. The internal temperature of the Tunnel of Fudge cake typically reaches about 180°F, which is high enough to kill common food borne pathogens, so it’s perfectly safe to eat!

How do you make this cake?

Making the tunnel of fudge cake is a little more labor intensive than just a typical bundt cake but don’t worry, it’s not THAT much more difficult.  The first step is to toast the nuts and cacao nibs by cooking them slightly on a dry skillet. Toast them on medium heat, shaking and stirring, until they darken slightly and smell fragrant. Then add a couple tablespoons of butter and some salt to the toasted nuts. You can skip the toasting step, but it really punches up the flavor to the nuts.

Then make the cake batter by placing the butter, sugar, brown sugar, vanilla, and salt in the bowl of a stand mixer and mixing all the ingredients together until it’s light and fluffy. This step is important because there’s no chemical leavening (baking soda or baking powder) in the recipe. This would alter the interior fudge layer. So you really need to mechanically add air into the batter by creaming the sugar and butter together.

Once you have a fluffy and cream mixture, drizzle cooking oil into the batter, and then beat a little espresso powder into egg yolks. Add then add in the espresso egg yolks mixture and beat until incorporated.

Add sifted powdered sugar (sifting makes sure the powdered sugar doesn’t clump) along with sifted cocoa powder. Add eggs slowly, then the flour. Fold in the toasted buttered nuts and cacao nibs.

Generously grease your bundt pan and then coat it with cacao powder. Spoon the batter into the pan and then place it in an oven that has been pre-heated to 400°F. Immediately lower the temperature to 350°F and bake for 40 minutes. No longer, no less. 

Once baked, let the cake cool on a wire rack. About 20 minutes after taking it in the oven, while the cake is still warm, press down on the cake, all the way around, to reduce the air gap that might form inside the “tunnel of fudge” part of the cake. Then let the cake cool completely in the pan, about 2 to 3 hours total from when you took it out of the oven.

Once cool, invert the cake pan over onto a cake stand or cake plate and sharply rap it on the countertop or table, to release it. Dust with powdered sugar or an optional chocolate glaze and serve.

Tips and substitutions for this cake

• Make sure you have the right oven temperature: This cake is dependent on having an accurate oven temperature, as you cannot test it in a traditional way with just a toothpick. The interior of the cake will stay fluid and will give you a false reading. Instead use an oven thermometer to make sure the oven is the proper temperature for the cake. If your cakes tend to take longer to bake than most recipes, then your oven typically runs a little cool and you might want to increase the temperature of the oven to 375°F. If cakes bake fast, then decrease the oven temperature to 325°F. Do not overbake this cake, or you will not get the tunnel of fudge in the middle, which is the cake’s namesake.
  
  If you have an instant read thermometer, you can use this to test the cake. The interior of the cake should read 180°F to 185°F, which is lower than the temperature of a done cake (which is usually 205°). Do not overbake this cake.

• Swap out cacao nibs: Cacao nibs are roasted cocoa beans, which is what chocolate is made out of. You can get cacao nibs at a well-stocked grocery store, an upscale grocery store, or online. If you don’t have cacao nibs, or prefer to make this without cacao nibs, just substitute out more nuts for the cacao nibs.

• Swap out nuts: If you aren’t a fan of nuts or are allergic, feel free to swap out all cacao nibs for the nuts. Or play around and use different nuts. Chopped pistachios, walnuts, pecans, hazelnuts and even macadamia nuts are all great options for this cake. I don’t recommend leaving out the nuts as it really makes this cake. But if you hate the texture of nuts in a cake, feel free to just leave them out

• Use the right bundt pan: This recipe works best with a heavy-duty sturdy metal pan. My favorite is Nordic Ware’s pans, which are cast aluminum and have a nonstick inside, which helps with the cake release. Thinner pans create hot spots and are not recommended. And even though I own numerous bundt pan shapes, I prefer to use the classic bundt pan shape, which has a large inside area that will allow the “tunnel of fudge” to form.
  
  Avoid silicone pans entirely. They seem like a great idea, as the flexible material means you cake can pop out easily. But the silicone material isn’t very sturdy and doesn’t retain heat, meaning the outer cake won’t brown and set as fast or as well as a metal pan. 

• Properly grease your pan: I use a generous amount of butter and cacao powder to make sure the can releases. You can use a baker’s cake spray, which has flour and cooking oil in, but I prefer to brush on melted butter or shortening onto the pan, making sure to get all the crevices. You can also use “cake goop” which is a mix of 1:1:1 ratio of melted shortening, cooking oil, and flour (think 1 tablespoon of each, or 1/4 cup of each ingredient). If you make a large batch of the cake goop, you can store in your pantry for up to a year. Brush the cake goop into any pan you want to release a cake.

How do you store the cake

This cake stores great at room temperature, under a cake dome, for up to 3 days or in the fridge tightly wrapped for up to 5 days. You can serve the cake at room temperature or cold. If you choose to serve the cake cold, the fudgy center will be more solid and truffle-like in texture.

If you like this Tunnel of Fudge Cake, check out these other chocolate recipes:

• Dark Chocolate Texas Sheet Cake
• Peppermint Texas Sheet Cake
• Cakey Brownies
• Guinness Stout Chocolate Bundt Cake with Irish Whiskey Ganache Glaze
• Double Chocolate Chip Muffins
• Easy Fudge Brownies
• Chocolate Banana Bread
• Bakery-style Chocolate Chips Cookies
• Neapolitan Brownies

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4.80 from 15 votes

Tunnel of Fudge Cake

This vintage cake features a slightly undercooked center that is fudgy and intensely chocolate in flavor. Make sure to follow the recipe exactly, no substitutions (other than the ones I listed above in my section on tips and substitutions). This cake relies on the oven temperature to be accurate as you cannot use the traditional toothpick test, as the undercooked “tunnel” will give you a false reading. If you undercook the cake, there won’t be a solid “baked” layer of cake on the outside to support the cake, and if you overbake cake, you’ll end up with a nice chocolate nutty cake, but no fudgy center.

If you are unsure about your oven temperature, use an oven thermometer, or use an instant read thermometer to test the doneness (it should be finished at 180°F to 185°F). And if you don’t own either of those, just go with your own experiences with your oven. If cakes you bake in the past tend to bake faster than the recommended time in recipes, your oven is running a bit hot, so drop the temperature down 25°. If previous cakes take longer to bake, then increase the oven temperature by 25°.

Course coffee time, Dessert

Cuisine American

Keyword bundt cake, chocolate, vintage

Prep Time 45 minutes minutes

Cook Time 40 minutes minutes

Rest Time 2 hours hours

Servings 12

Calories 566kcal

Author Irvin

Ingredients

Inclusions

• 1 cup chopped pecans 120 g (can substitute another chopped nut, see note above)
• 1 cup cacao nibs 115 g (see note above, can be substituted with more nuts)
• 2 tablespoons butter melted
• 1/4 teaspoon kosher salt

Batter

• 1 1/4 cups unsalted butter at room temperature, 285 g or 2 1/2 sticks
• 1 cup white sugar 200 g
• 3/4 cup brown sugar 165 g
• 2 teaspoon vanilla extract
• 1/2 teaspoon kosher salt
• 1/3 cup vegetable oil 65 g
• 2 large egg yolks
• 1 teaspoon espresso powder optional but recommended
• 2 cups confectioner’s sugar powdered sugar, sifted, 230 g
• 3/4 cup natural cocoa powder sifted 70 g
• 4 large eggs
• 2 cups all-purpose flour 280 g
• For pan
• 2 tablespoons melted butter shortening or cake goop (see section above)

To finish

• Powdered sugar or optional chocolate glaze (see note below for chocolate glaze recipe)

Instructions

• Preheat the oven to 400°F.

  Place the chopped pecans and cacao nibs in a dry skillet. Cook on medium heat, stirring and shaking the pan frequently, until the nuts and cacao nibs start smelling fragrant. Immediately remove from heat and drizzle the melted butter over it and sprinkle with salt. Toss to coat and set aside to cool.
  
• Make the cake batter by placing the butter, white sugar, brown sugar, vanilla, and kosher salt in the bowl of a stand mixer. Mix on low speed, increasing to medium speed, mixing the ingredient together until the entire mixture is fluffy and light in texture and color, scraping down the bottom and sides of the bowl occasionally, to make sure all the ingredients are fully incorporated.
  
• Beat the oil, egg yolks and espresso powder together. Reduce the speed to low, and then drizzle the mixture into the bowl, making sure to incorporate it fully. Scrape down the sides and bottom of the bowl.
  
• Add the sifted powdered sugar and cocoa powder to bowl, and slow mix to incorporate. Then add the eggs, one at a time, mixing and scraping down thoroughly between each addition.
  
• Add the flour and the buttered nuts (the butter should have cooled around the nuts). Gently fold these ingredients in, either on low speed, or by hand with a large flexible spatula.
  
• Brush a metal bundt pan with melted butter, shortening, or with cake goop (see section above). Dust with cocoa powder. Gently spoon the batter into the pan, smoothing it out to make sure the cake batter is evenly distributed in the pan.
  
• Place the pan in the oven, then immediately reduce the heat of the oven to 350°F. Bake for 40 minutes. Do not test the cake with a toothpick, instead you have to rely on the accuracy of the oven. See my note above in regard to this.

  Remove the cake from the oven and let it sit on a wire cooling rack for 20 to 30 minutes. Then press down on the cake all the way around, to reduce any air pockets that might have formed around the “tunnel of fudge” inside the cake. Then let the cake completely cool, a total of 2 to 3 hours.

  Once cooled, gently loosen the cake with a thin knife around the edges of the pan. Then invert the pan onto a cake platter or cake stand. Sharply tap it onto the counter or tabletop to release the cake.

  Dust the cake with powdered sugar or glaze it with a simple chocolate glaze (see note below for the chocolate glaze). Slice carefully, as the inside of the cake will have a fudgy interior filling.
  

Notes

Optional chocolate glaze: This cake is plenty chocolate fudgy on its own, especially with the addition of the cacao nibs, so I usually just dust it with a little bit of powdered sugar and serve it as is. But if you want to take it over the top, you can make a chocolate glaze and drizzle it on it before serving.

To make a chocolate glaze, melt 2 ounces (57 g) of chopped dark chocolate or semi-sweet chocolate chips with 2 tablespoons (1 ounce or 28 g) of butter in a microwave safe bowl, cooking in bursts of 30 seconds and stirring between each cycle. You can also melt the chocolate and butter in a double boiler or directly in a pot on low heat. Once melted sift in 1 cup (115 g) of powdered sugar, stirring to dissolve.

Mix in 2 tablespoons of warm milk or cream and stir until the glaze is fluid. You can add more milk or cream as necessary. Pour or drizzle the glaze over the cake once it is cool to room temperature. Keep in mind the glaze will solidify as it cools so if you make ahead of time, you might want to warm it up in the microwave a bit to make it more fluid.

Nutrition

Calories: 566kcal | Carbohydrates: 52.6g | Protein: 11.6g | Fat: 32.7g | Saturated Fat: 10.8g | Cholesterol: 354mg | Sodium: 320mg | Potassium: 347mg | Fiber: 4.1g | Sugar: 33.9g | Calcium: 71mg | Iron: 3mg

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