This is from Arthur Schwartz, as cited on e-Gullet:
According to Jean-Georges, the cake was not deliberately developed but the result of a mistake. He pulled a classic chocolate pain biscuit (sponge cake) from the oven too soon and it had a runny, but very delicious center.
That was back in 1987, when Vongerichten was the highly acclaimed chef at Lafayette, the dining room in the Drake Hotel. At first he served the liquid-center cake as a petit four. It became so popular he began to make in a larger version. Now, molten chocolate cake is everywhere, a best-seller all across the U.S.
Paula Wolfert asserts that it's from the early 1980s, and either from Jacquie Chibois working at the Grey Albion in Cannes, or from Michel Bras.
Perhaps this article straightens things out. Hey, Jean-George, if you got the recipe from your mother, why call it an accident?
27 November 1991, New York Times, pf. C3:
The Cakes That Take New York Erupt With Molten Chocolate
By FLORENCE FABRICANT
The confection in question is a small warm chocolate cake that, when cut, oozes with intensely rich molten chocolate. This year, some version of it is being served in more than a dozen restaurants. New ones are added to the list almost daily.
"Sirio wanted me to put it on the menu," said Jacques Torres, the pastry chef at Le Cirque, referring to Sirio Maccioni, the owner. "A lot of people were asking for it."
Mr. Torres said he was familiar with similar desserts in several restaurants when he worked in the south of France. "Now it has become very popular here," he said. "Nobody has exactly the same recipe, and to tell the truth it's really very simple, nothing exceptional, but everyone seems to love it."
Francois Payard, the new pastry chef at Le Barnardin, said he had prepared desserts like that when he worked with Alain Senderens at Lucas-Carton in Paris. Taillevent, another Parisian restaurant, is also sometimes mentioned as a source.
But Jean-Georges Vongerichten, the chef and co-owner of Jo Jo, exclaimed when asked about the runny little chocolate cakes, "They're mine, they're mine!" At Jo Jo's the dessert is called chocolate Valrhona cake with vanilla ice cream.
"Maybe there is a surprise factor," said Lois Freedman, the manager of Jo Jo. "The description on the menu doesn't prepare people for what to expect. But it's becoming like a cult thing, with people saying it's the best dessert they ever had. We sell more of those cakes than any other dessert."
Miss Freedman said the phenomenon was especially curious because Mr. Vongerichten, who said he got the recipe from his mother, served the same dessert at Lafayette for two years before opening Jo Jo, yet it had much less impact there.
For his part, Mr. Ducasse said he started making the cake some five years ago, but did not invent it. "It reached a point where we were practically obliged to make it, but when it began showing up in every restaurant I took it off the menu," he said.
Mr. Colicchio of Mondrian said his chocolate ganache cake comes from Michel Bras, a Michelin two-star chef whom he worked with in the summer of 1989. It's more complicated, involving a piece of chilled truffle-like ganache, which is a mixture of cream and chocolate, embedded in a simple cake batter in a small mold. THis assembly is frozen overnight so that when it is finally baked, the ganache center softens and melts inside.
:It's our best-selling dessert," he said. "And I think I was the first to do it." He said that recently, some food writers and cooking teachers who had dinner in his restaurant criticized the dessert for being underbaked.
Mr. Yosses began making his dessert when he was at Montrachet and continues to prepare it at Bouley. It is a small fallen souffle, warm and still moist in the middle. He said he learned it from Roger Verge.