Tunnel of Fudge

This is the legendary bundt cake that made the bundt pan famous. The “tunnel” is a ring of soft, fudgy chocolate that forms naturally inside the cake as it bakes. The outside sets into a dense, brownie-like crumb while the center stays gooey and molten. No lava cake insert, no trick. It just happens.

The secret is the dry frosting mix stirred into the batter along with the flour. That concentrated chocolate-sugar powder creates a zone in the middle of the cake that never fully sets, giving you that signature fudge tunnel when you slice into it. Six eggs and a pound and a half of butter make the surrounding cake incredibly rich and dense.

Two cups of walnuts (or pecans) go into the batter and add crunch throughout. They also help create structure in the cake that supports the soft center without collapsing.

You can’t test this cake with a toothpick like normal. The center is supposed to be gooey. Instead, look for a dry, shiny, brownie-type crust on top at the 60-minute mark. Cool it in the pan for a full 30 minutes before turning out, or the tunnel collapses.

Chef Tips

• Do not substitute the dry frosting mix. It’s what creates the fudge tunnel. Regular cocoa powder won’t work the same way
• Beat the butter and sugar until truly light and fluffy. This takes longer than you think, at least 5 minutes on high speed
• Grease and flour the bundt pan thoroughly. Every ridge is a potential disaster zone for sticking
• Cool in the pan for exactly 30 minutes. Too soon and it collapses, too long and it fuses to the pan

Variations

• Pecan version: Use pecans instead of walnuts for a slightly sweeter, more buttery nut flavor
• Glaze finish: Drizzle with a simple chocolate ganache after cooling for an extra-rich presentation