The United States Patent and Trademark Office (USPTO) approved the Cronut trademark after Dominique Ansel filed for it.
Dominique Ansel introduced the Cronut at his bakery in New York’s SoHo neighbourhood on 10 May 2013. The pastry combines croissant-style laminated dough with the shape and frying method associated with a doughnut, then receives a flavoured cream filling and toppings.
The name quickly became famous after a food blog reported on the pastry, drawing large queues to the bakery. Ansel filed for a trademark for “Cronut” within nine days of introducing it, and the application was approved by the USPTO. That is why the answer is not WIPO, even though WIPO is a major international intellectual-property organisation, nor the FDA, which regulates food and medicines rather than trademarks.
The trademark protects the name in the relevant legal context; it does not mean Ansel invented every croissant-doughnut hybrid. Similar pastries appeared under alternative names after the Cronut became popular, partly to avoid using the protected brand name.