Rich Tunnel Fudge Cake

This decadent tunnel of fudge cake is a retro classic! It became famous after the 1966 Pillsbury Bake-Off, thanks largely to its rich chocolate flavor and gooey, fudge-filled center.

It’s a fascinating piece of American baking history.

When Ella Rita Helfrich made it for the competition, it sparked a nationwide obsession. It became more challenging to make when Pillsbury discontinued its Double Dutch Frosting Mix.

But this recipe uses everyday pantry staples to replicate it! Yay!

Ingredients

• Unsweetened Cocoa Powder: It provides a deep, rich chocolate flavor. It’s essential for creating the fudge center and the intense chocolate glaze.
• Butter: For richness and a tender crumb and moist texture.
• Granulated Sugar: It ensures a light and fluffy cake while adding sweetness.
• Eggs: The cake’s “structure builders.” They hold everything together and help the cake rise.
• Vanilla Extract: It enhances the overall flavor and cuts the chocolate’s richness for a balanced taste.
• Powdered Sugar: It provides sweetness and helps achieve a fine, smooth texture in both.
• All-Purpose Flour: The foundation of the cake absorbs the wet ingredients to create a cohesive batter.
• Semi-Sweet Chocolate Chips: They melt into warm pockets within the cake for maximum gooeyness.
• Milk: It helps achieve the perfect glaze consistency, so it’s pourable but rich.

How to Make Tunnel of Fudge Cake

Prepare:

Preheat the oven to 350 degrees. Grease a 12-cup Bundt cake with nonstick spray and dust it evenly with a tablespoon of cocoa powder. Tap out any excess and set it aside.

Cream the butter and sugar:

Cream them using a stand mixer with the paddle attachment at medium speed. Continue until light, fluffy, and nearly doubled in volume. Scrape the sides as needed.

Add the eggs and vanilla:

Mix each egg in fully before adding the next. Add the vanilla along with the final egg.

Add the sugar:

Reduce the mixer speed to low. Slowly add 2 cups of powdered sugar. Mix well.

Combine:

Whisk the flour and 3/4 cup of cocoa powder in a separate bowl. Gently fold the dry ingredients into the wet mixture. Add the chocolate chips when the two are just combined.

Bake:

Evenly pour the batter into the pan, and bake for approximately 1 hour.

Cool:

Remove the cake from the pan and cool it in its pan on a wire rack for 90 minutes. Then, invert it carefully onto the rack to cool completely.

Make the glaze:

Whisk 3/4 cup of powdered sugar, 1/4 cup cocoa powder, and 2 tablespoons of milk in a small bowl. Add more milk slowly, as needed, to adjust the consistency.

Finish and serve:

Drizzle the glaze over the fully cooled cake. Let it set slightly, then slice, serve, and enjoy!

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Tips for the Best Tunnel of Fudge Cake

I have several tips for this one! Check them out before jumping to the recipe card below:

Quality cocoa is key. Dutch-processed cocoa is my favorite. It gives the cake a deeper, more intense chocolate flavor. You can stick with natural cocoa for a slightly lighter, classic taste. Just be sure to get a high-quality brand for the best taste.

Prep the pan thoroughly. Bundt pans have nooks and crannies that are “great” for sticking. Greasing and dusting with cocoa powder ensures an easy release and prevents that issue. Always tap out excess cocoa for a smooth exterior.

Make the mixture fluffy. Whip the butter and sugar until they’re fluffy and doubled in volume. Doing so helps create a lighter structure and locks in air for a velvety texture.

Go easy on the eggs. Incorporate one egg at a time, mixing it fully before adding the next. This gradual approach boosts emulsification and guarantees a consistent batter.

Don’t overmix! Gently mix the flour-cocoa blend into the wet ingredients. Overmixing can toughen the cake and compromise its fudgy center.

Test for doneness. Unlike most cakes, the center of this cake will (and should) remain slightly gooey. Look for set edges and a top that’s no longer shiny as signs that it’s ready.

Try fun flavor tweaks. For variations, fold in chopped nuts or swirl in peanut butter. You can even add a dash of espresso powder to enhance the chocolate flavor.

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How to Store

Storing this cake is a simple process! Here’s how.

To Store: Keep it in an air-tight container in the fridge for up to 3 days. Bring it to room temperature before serving to enjoy its best texture and flavor.

To Freeze: Wrap the cake tightly in plastic wrap and aluminum foil. Or place slices in freezer-safe bags. Freeze for up to 3 months. Thaw overnight in the refrigerator before serving.

To Reheat: Warm individual slices in the microwave for 30-45 seconds. You can also reheat the whole cake in a 300-degree oven. Wrap it in foil and heat it for about 10-15 minutes to maintain moisture.

Frequently Asked Questions

→ What creates the tunnel effect in this cake?

The tunnel is formed by melting semi-sweet chocolate chips inside the batter during baking, creating a molten fudge center.

→ How can I ensure the cake comes out of the bundt pan cleanly?

Grease the pan thoroughly and dust it with cocoa powder, tapping out excess, to prevent sticking in the pan’s crevices.

→ Can I use natural cocoa powder instead of Dutch-processed?

Yes, natural cocoa can be used but will yield a lighter, more classic chocolate flavor compared to Dutch-processed’s deeper taste.

→ How do I know when the cake is perfectly baked?

The edges should be set, and the top no longer shiny, while the center remains slightly gooey to maintain the fudge tunnel texture.

→ What’s the best way to store leftovers?

Store the cake in an airtight container in the fridge for up to 3 days or freeze tightly wrapped for up to 3 months.

→ Can I add variations to the flavor?

Yes, try folding in chopped nuts, swirling peanut butter, or adding espresso powder to enhance the chocolate richness.