Mr. Jeanson and the jury decided to model the cake on the dome of the interior of the Opéra Comique and he chose to dust it with a deep magenta powder made from raspberries. Inside was a traditional pale pink sponge cake similar to the kind made in Reims, Favart’s home city in northeastern France, where his father was a pastry chef. The final touch was a single gold leaf chosen by Ms. Moaty, after the jury considered 16 different decorative possibilities.

Mr. Jeanson said he had never been to the opera before he set out to make the cake, but he quickly found a like-minded artistic ally in the leader of the orchestra.

“We realized that our work was in completely the same spirit, “ Mr. Jeanson said. “I said to him, ‘You are the orchestra chief. You have all prime materials. You know how to marry them, how to make them dance together. Each one has his place.’”

He added: “Just as the one who makes the sponge cake makes it as he should and the same for the cream. Our intention is that you have these emotions, in tasting or in coming to see the performance.”