Chewy, crunchy and not-too-sweet, round, chocolatey “Dubai-style” cookies have become the must-have dessert in South Korea — with the rush for the snacks even prompting the Red Cross to offer them as a draw for blood donors.

Springboarding off a global craze for “Dubai chocolate” — a pistachio-filled chocolate bar layered with fine shredded pastry known as kadaif — and fueled by K-pop endorsements, “Dujjonku” have become a phenomenon in South Korea.

Online searches for the dessert surged more than twenty-fold in the last three months, according to data from Naver, the country’s largest search engine.

Searches on food delivery apps for the snacks jumped by 1,500 times last month.

And one developer even created an online map to track which shops still have stock remaining — convenience store versions have also repeatedly sold out.

Customers have lined up outside shops in the early hours of the morning, even as temperatures have plunged in South Korea’s bitter winter.

“Even without much initial interest, once you hear that everyone else is eating it, you start wondering just how good it must be,” Nam Su-yeon, a 28-year-old office worker, told Agence France-Presse.

“That curiosity leads you to buy it and try it once, then to think another place might be even better,” she said.

To make them, cafes melt marshmallows to create a chewy outer layer mixed with chocolate, then fill individual portions with pistachio cream and kadaif before dusting the top with cocoa powder.

They don’t come cheap —weighing at just 50 grams, the average price for the dessert currently stands at 6,500 won ($4.40).