The Mcdonald Sandwich - named after its inventor Scott Macdonald - is set to go on sale on Monday at Selfridge's on London's Oxford Street.

Weighing in at just under half a kilo, the cost of the triple-decker is largely due to its main ingredient - gourmet Japanese Wagyu beef, regarded as being one of the finest and most expensive meats in the world.

The meat is pan-seared before being basted with foie gras and chilled for 15 minutes.

The sandwich itself is made from fermented sour dough bread spread with a foie gras and black truffle flavoured mayonnaise.

Also included are large slices of one of the world's finest cheeses - brie de meaux.

The creation is rounded off with English cherry tomatoes, rocket and peppers that have been roasted over a naked flame.

Georgio Locatelli, a chef who tasted the gourmet snack for the Sunday Telegraph newspaper, said the sandwich was an "utterly fantastic mixture of tastes ... the beef simply melts, I'm impressed".

Sake and beer

Wagyu beef is derived from pampered Japanese Kobe cattle - animals that live in luxurious conditions that are reflected in the meat's high price.

Each animal is reared in an individually heated stall and fed on top-quality grain whilst exercise is restricted, ensuring that each beast grows to reach mammoth proportions.

During the fattening process, the animals are fed sake and beer to increase their appetites and the lucky ones even enjoy the services of masseur - a treatment that is meant to make the meat more tender.

Selfridges has already received five advance orders for the sandwich, the newspaper said.