Lest trademarking a croissant/donut seem absurd, there is ample precedent. Chefs, or more often, big food companies, can protect the names of their unique products -- think Boardwalk Fries, or Coca-Cola, or Big Mac. Recipes or lists of ingredients cannot be trademarked, nor can traditional dishes, like a hamburger or ramen. Still, "The Cronut® is a little bit of an unusual case," says Julian Cordero, attorney and managing member at Cordero Law LLC in New York City -- a rare, ballsy legal move, as it's usually a major corporation that takes this step, not a small, single bakery. "It's not necessarily the fact that it's a food, it's the name you provide that is important for a trademark," Cordero explains.
Which means you are entirely free to market and sell your own donut/croissant, so long as you don't call it a Cronut®. Many have -- the Croissant Donut from Dunkin' Donuts was introduced in 2014, and you can get a "dossant" or a "doissant" from enterprising spots in DC, Sacramento, and as far as Australia. But the Cronut® name is sacred, and those who have tread on it have been swiftly blocked. Cook issued a cease & desist to a Santa Monica bakery that dared sell a "Kronut," with a "K," and one to Reno's Rounds Bakery, which was offering a "croissant donut." At Gertrude's, the upscale restaurant in the Baltimore Museum of Art, pastry chef Doug Wetzel re-imagined the pastry as a donut "hole" and served it with whipped cream and lemon curd. He called his creation the "croi-nut." He received a cease & desist from Cook, too. (Dunkin's pastry had a non-Cronut®-enough name to deem it not confusing to customers, and therefore safe from legal action.) "Changing the spelling of the word 'Cronut'® when the resulting change is phonetically similar to the DA Bakery's trademark is a deceptive attempt to usurp the DA Bakery's intellectual property rights and is punishable under federal law," the letter to Gertrude's read.