RIKERS ISLAND, N.Y.—On Christmas, the dinner menu at one of the nation’s most notorious jail complexes will include roast beef au jus, baked potatoes, whole-wheat bread and mixed vegetables. But there won’t be Christmas cookies for dessert.

“The carrot cake is the pièce de résistance,” said E. Glenn O’Connor, the New York City jail system’s director of nutritional services.

Paris has croissants. Belgium has waffles. And Rikers Island has carrot cake. The spiced loaf is the jail’s most famous food and the only dessert served on holidays.

The jail’s more than 50-year-old bakery produces about 2,500 loaves annually, resulting in 62,500 slices served (without frosting) on occasions including Thanksgiving, Christmas and the end of Ramadan.

“It’s synonymous with Rikers,” said Mr. O’Connor, whose prior jobs involved feeding people in other captive situations, including in airplanes and hospitals. “It’s built into the culture that that’s the expectation.”