Some call Costco’s new burger ‘Shake Shack copycat’

Some Costco locations are serving up a new burger -- and it’s causing chatter beyond the food court. 

>> Read more trending news

Observations of the new burger have circulated for weeks, and it’s making headlines because food critics are comparing it to a Shake Shack burger.

Shake Shack, a popular chain that hasn’t made it to the northwest U.S., builds its burger with all-natural Angus beef, a “Chicago-style” potato bun, the Shack's sauce, which is made up of mayo, dijon mustard and dill pickle brine.

>> Related: Dick's Drive-In makes ‘25 Best Cheeseburgers' national list

“The final product looks nearly identical to Shack's beloved burger, though the ingredients are slightly different,” wrote Delish.com's Rheanna O’Neil Bellomo, who simply called it a “Shake Shack copycat.”

Ingredients in the 1/3 pound Costco burger are reported to be an organic beef patty, topped with romaine lettuce, and smoke Thousand Island dressing.

>> Related: This essay about Costco got a high school senior into 5 Ivy League schools

When the Seattle Times checked in with Costco Corporate about Seattle as a test market, it wouldn’t confirm the cheeseburger. But a reporter found one for sale at the Costco location in SoDo, costing a modest $4.99 and not-so-modest 1,140 calories.

According to Eater, the burger is in a localized testing phase.