The British retailer Marks & Spencer will bring cartons of guaranteed double-yolk eggs to its food department, giving discerning egg-lovers the promise of more essential fats, vitamins and minerals per egg.

A rare phenomenon in egg productions, with only one in every 1,000 eggs having two yolks, Marks & Spencer says it will separate the super ova from the rest with a process known as ‘candling’; this means every egg handled by the retailing giant will now be personally inspected by placing it in front of a very bright light bulb to reveal the shadow of the yolks inside.

"We’re really excited to be selling double yolkers,” said M&S product developer Ali Rodham. “We think they’re cracking, and we’re sure our customers will too.”

"Perfect for people who think the yolk is the best bit of the egg, double yolkers are not only delicious, but they are healthy too," Rodham added.

Eggs, once considered a questionable choice in terms of maintaining a healthy diet, recent research has debunked many of those theories; eggs contain vitamins B12, B6, A, K, E, almost all of which are not found in the whites. Yolks, considered the nutritional centre of the egg, are also one of the few natural foods containing vitamin D.

The M&S British Free Range "Double Yolkers" are available now for £2.75 (€3.70) for a box of six.