The world's largest McDonald's and the flagship outlet in Olympic Park, London, is pictured June 25, 2012. Oli Scarff/Getty Images

McDonald's Corp. is set to supersize its burgers in the United Kingdom. While not exactly returning to the long-scrapped gut-busting portions of yore, the fast-food chain is expected to roll out a brand of premium burgers with thicker patties in the U.K. aimed at keeping up with competition like Byron and Shake Shack, the Wall Street Journal reported Wednesday.

The company said the new burgers would be made entirely from British and Irish beef. Perhaps in an effort to distinguish the premium burgers from your run-of-the-mill McDonald's sandwich, the new offerings will be served in black packaging, with the accompanying French fries in a matching carton.

The burgers will we priced at about 4.69 pounds ($7.21) alone, or 6.19 pounds ($9.52) for a meal, and are expected to be sold on a trial basis starting Wednesday in London, the South East and Manchester. Starting next summer, they will reportedly be offered as a permanent item on menus at about 400 McDonald's restaurants across England.

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The thicker patties will take a bit longer to cook, so customers ordering the black-boxed burgers should expect a longer wait time. If enough people are willing to pay up and wait for the premium patties -- the trial proving successful -- the chain said it could try a number of other new offerings, including allowing customers to customize classic burgers, order and pay by smartphone, and charge smartphones using wireless charging devices, according to the Journal.

Amid increased competition, especially from "fast-casual" restaurants, McDonald's had a promising quarter after a slew of bad results. Global sales were up a better-than expected 4 percent in the third quarter, ending six straight quarters of flat or declining results, according to Reuters last month. It was taken as a sign that a turnaround was underway.

"The progress we have made in a short amount of time gives me confidence we're making the right moves to turn around our business and reposition McDonald's as a modern, progressive burger company," CEO Steve Easterbrook said at the time during a conference call with analysts and investors.

McDonald's has struggled in the U.K. to keep up with increased competition, and research firm Mintel last year projected the chain to see a decline in customers 20 to 24 years old, the Journal reported. The chain previously set a target of opening 40 new U.K. restaurants each year, starting in 2014. The company has also tried out different premium options in other European countries, including a burger made of 100 percent organic beef in Germany this October.