The Asador Aupa restaurant in Spain serves the world’s most expensive and special burger. It costs $11,000 and can only be experienced by those invited by the restaurant.

Burgers have gotten considerably more expensive in recent years, but they remain among the most affordable food items on restaurant menus. There are a few exceptions, though, the most notable of which recently claimed the title of “the world’s most expensive burger”. Thought up by the chefs at Asador Aupa, a Basque cuisine eatery located in Cabrera del Mar, Catalonia, this special treat reportedly took eight years of research and experimentation to develop, and its exact ingredients remain a secret. All we know is that the burger’s heart-stopping €9,450 ($11,000) price tag is linked to quality ingredients, and a unique dining experience.

Asador Aupa was founded by Bosco Jiménez, better known as BdeVikingo, a Spanish chef known for his love of the Basque cuisine. His concept for the world’s most expensive burger was simple — “luxury shouldn’t be noisy, it should be unattainable.” Few people can afford to pay $11,000 for a burger, but even having amounts of money isn’t enough. To try the world’s most expensive burger, you have to be invited by Asador Aupa.

Only those who meet all the requirements are invited to try the world’s most special burger, but here’s the kicker: no one knows what the requirements are. However, if you do get selected by Asador Aupa, you will be invited to a private room of the restaurant, seated at a table with a few other lucky customers, and served a delicacy cooked with the “three best meats in the world”, “the most special cheese in Europe”, and a special sauce prepared with a luxury spirit.