Sinful Fudge Tunnel Cake

The “tunnel” effect is achieved through a simple yet strategic layering method. First, a little more than half of the plain vanilla batter is spooned into the bottom of your well-greased Bundt pan. This forms the base of the cake. Next, the rich chocolate fudge batter is carefully poured in a continuous ring over the plain batter. It’s important to position this chocolate ring equidistant from the pan’s edges, ensuring it sits in the middle as the cake bakes. Finally, the remaining plain batter is gently poured over the top, completely encasing the chocolate layer. During baking, the two batters set, creating that iconic fudgy “tunnel” nestled within the vanilla cake.

Successfully releasing a Bundt cake hinges on two critical factors: proper pan preparation and appropriate cooling time. First, ensure your pan is meticulously prepped by coating every inch with a layer of softened butter, then dusting it with flour (tapping out any excess). Alternatively, a reliable flour and oil baking spray can be used. Inspect older pans for signs of wear or scratches, as these can be trouble spots. After baking, the cake must cool in the pan for approximately 10 to 15 minutes. This window allows the cake’s delicate crust to firm up, providing structural integrity for removal. If you attempt to remove it too soon, the cake may crumble; if you wait too long, it can get “stuck” as the sugars cool and adhere to the pan. Once cooled for the appropriate time, gently jiggle the pan back and forth to loosen the cake, then carefully invert it onto a wire rack to finish cooling completely.

Determining doneness for a Bundt cake is similar to other cakes, primarily relying on the toothpick test. About 5-10 minutes before the recommended baking time ends, insert a clean wooden toothpick into several spots in the thickest part of the cake, avoiding the fudgy center if possible. If the toothpick comes out completely clean, the cake is done. If it has wet batter clinging to it, continue baking and recheck in 5-minute intervals. If you see only a few moist crumbs clinging to the toothpick, this is generally acceptable, as residual heat will continue to cook the cake slightly as it cools outside the oven. The top should also spring back gently when lightly touched.

The original Tunnel of Fudge Cake recipe gained legendary status as the grand prize winner of the Pillsbury Bake-Off in 1966, created by Ella Helfrich. Her groundbreaking recipe famously used a package of Pillsbury Double Dutch Frosting Mix, which contributed to its unique fudgy texture. However, when the frosting mix was discontinued, the original recipe became difficult to replicate. This particular nut-free version is a modern adaptation shared by a blogger friend (whose blog is no longer active), skillfully recreating that signature fudgy ribbon without the discontinued mix or nuts, making it perfect for families with allergies or preferences.

While the recipe specifies semi-sweet chocolate for a balanced sweetness, you can experiment with other types. Dark chocolate will yield a more intense, less sweet fudge, which can be delightful for those who prefer a richer cocoa flavor. Milk chocolate would result in a sweeter, creamier fudge. Just be aware that adjusting the type of chocolate will alter the final flavor profile of your “tunnel.”

To maintain its freshness and moisture, store the Tunnel of Fudge Cake at room temperature in an airtight container for up to 3-4 days. If your kitchen is particularly warm, or if the cake contains perishable fillings (which this one does not), you might consider refrigerating it. However, refrigeration can sometimes dry out cakes, so room temperature is generally preferred for optimal texture. For longer storage, the cake can be frozen.

Ingredients

Cake:

• 3 cups all-purpose flour
• 2 ½ teaspoons baking powder
• ½ teaspoon baking soda
• 1 teaspoon salt
• 10 ounces semi-sweet chocolate, chopped and divided (6 ounces for cake, 4 ounces for glaze)
• 1 ½ cups (3 sticks) unsalted butter, at room temperature
• 1 ⅔ cups granulated sugar
• 1 teaspoon pure vanilla extract
• 3 large eggs, at room temperature
• 1 cup whole milk
• ½ cup sour cream

Glaze:

• 2 tablespoons light corn syrup
• ½ cup heavy cream
• Reserved 4 ounces semi-sweet chocolate

Instructions

1. Butter and flour, or spray with a flour and oil baking spray, a 12-cup capacity Bundt pan. Set aside. Preheat your oven to 350ºF (175ºC).
2. In a medium bowl, combine the flour, baking powder, baking soda, and salt. Whisk these dry ingredients together thoroughly to ensure even distribution. Set aside.
3. Melt 6 ounces of the chopped semi-sweet chocolate in the microwave. Heat in 30-second intervals, stirring after each, until the chocolate is completely melted and smooth. Set aside to cool slightly.
4. In a large mixing bowl, using an electric mixer, beat the room temperature butter, granulated sugar, and vanilla extract until the mixture is light and fluffy, usually 3-5 minutes. Add the eggs one at a time, beating well after each addition until fully incorporated.
5. In a separate bowl (a Pyrex 2-Cup Glass Measuring Cup works well), whisk together the milk and sour cream until combined.
6. With your mixer on low speed, alternately add the dry flour mixture and the milk-sour cream mixture to the wet batter, beginning and ending with the flour mixture. Mix until just smooth, being careful not to overmix.
7. Spoon about 1 cup of this plain batter into the slightly cooled melted chocolate. Stir until well combined. The chocolate should be warm, not hot, before adding the batter to prevent it from seizing.
8. Spoon slightly more than half of the plain batter into the bottom of your prepared Bundt pan.
9. Carefully add the chocolate batter in a distinct ring over the plain batter, ensuring it’s not touching the pan walls. Follow this with the remaining plain batter, completely covering the chocolate layer. If needed, gently smooth the top with an offset spatula.
10. Bake for 55-60 minutes, or until a wooden toothpick inserted into the center of the cake (avoiding the chocolate tunnel) comes out clean or with a few moist crumbs.
11. Allow the cake to cool in the pan for about 10 minutes. Then, carefully invert it onto a wire rack to cool completely.
12. To make the glaze: In a microwave-safe bowl, combine the reserved 4 ounces of chopped chocolate with the light corn syrup and heavy cream. Microwave for 1-2 minutes, stopping and stirring every 30 seconds, until the mixture is smooth and melted. Let the glaze cool slightly to thicken.
13. Once the cake is completely cool, place it on the wire rack set over a baking sheet (lined with parchment paper for easy cleanup). Spoon the slightly cooled glaze evenly over the cake, allowing it to drip down the sides.
14. Allow the glaze to firm up at room temperature before slicing and serving. If making a Tunnel of Doom cake, add seasonal sprinkles immediately after glazing.

Notes

Recommended Products

As an Amazon Associate and member of other affiliate programs, I earn from qualifying purchases.

• Baker’s Joy Spray
• Pyrex Measuring Cups
• Nordic Ware Bundt Pan

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