“Throw reason and restraint to the wind before you begin,” advised the Swarthmore professor Eugene Weber, when he passed along the recipe of the original Rosenkavalier torte to Craig Claiborne, the American taste-maker supreme and food editor at The New York Times. Whipped up in honor of the beloved Richard Strauss opera, this triple-tier indulgence of mixed nuts, chocolate, and jam was the creation of Mrs. Hugo von Hofmannsthal, wife of the celebrated Rosenkavalier librettist. Her frosting alone called for a pound of butter. She said to slice servings very thin.

Even music-lovers who eat up Der Rosenkavalier sometimes blanch at the empty calories. Nevertheless, the white-on-silver, powdered-wig window dressing of tradition has proved hard to shake. At the Metropolitan Opera, it wasn’t until 2017 that Der Rosenkavalier got the kind of radical reboot that is de rigueur in Europe for repertoire across the board. With the rococo froufrou much reduced, this is the version that will be streaming for 23 hours beginning on Sunday, April 19, at 7:30 p.m. E.D.T., one in a daily rotation of free encores from the company’s chockablock live-HD archive.