This unusual cake -- yes, there really is a tunnel of fudge running through its center -- was the creation of Ella Rita Helfrich who won second prize in the 1966 Pillsbury Bake-Off. (For her efforts, she received $5,000; the first place winner took home $25,000 for a bread made with cheese spread and onion soup mix.)
For a second place winner 44 years ago, this cake has legs. First, it popularized (or saved from extinction) the bundt pan, which was only rarely used at the time. (Its legacy is enduring; many remember the small, yet pivotal role the "cake with a hole in it" played in the film, My Big Fat Greek Wedding.) Pillsbury reported that it received 200,000 calls from home bakers looking for bundt pans following the 1966 contest.
Was it good? Yes, though it seemed more like a brownie than a cake, not that there's anything wrong with that! The brownie reference may be due to the two cups of walnuts in the recipe. One is instructed not to skimp on the nuts, as they are considered critical to the formation of the gooey center. Most experts in the chemistry of baking attribute the tunnel creation to the excessive amount of sugar in the recipe.
2 1/4 cups all-purpose flour
1 3/4 cups granulated sugar
6 large eggs
2 cups confectioners' sugar
3/4 cup unsweetened cocoa powder
2 cups chopped walnuts
1/4 cup cocoa powder
1 1/2 to 2 tablespoons milk