What is a flying dutchman at in n out?

At In-N-Out, a Flying Dutchman is a secret menu item that consists of two beef patties sandwiched between two slices of cheese. It is called a Flying Dutchman because it is a "burger" with no bun. Customers can customize it with additional toppings such as lettuce, tomato, and onion. The Flying Dutchman is popular among low-carb and keto diet followers as it is a high-protein, low-carb option.