Privately held White Castle, which operates nearly 380 restaurants in the U.S., launched an experiment this past spring that’s in some ways even more radical than fresh beef:

The Run Up

It began testing a $1.99 Impossible Slider, built around a highly-con­vincing plant-based patty made by Impossible Foods that chars and releases juices upon cooking. White Castle marketing head Kim Bartley became interested in meat alternatives a few years ago and asked the chain’s director of innovation and head chef to keep an eye out. “They brought the Impossible to me and I was blown away,” she says. White Castle and Impossible Foods worked on the patty throughout 2017; within 18 months of Bartley’s first taste, the slider was on test-market menus.

The Rollout

The Impossible Slider, released April 12 in 140 outposts in New York, New Jersey, and Chicago, was aimed less at vegetarians and vegans than the more than 26% of Americans looking to eat less meat. Unlike the beef sliders, which are steam grilled, the Impossible Slider is cooked to order on the grill. Each sandwich takes around three minutes to prepare.

The Response

Social media lit up with posts about the burger. “I can’t even tell you the multiple on social,” says Bartley, who notes the chain has also recently scored buzz via its new uniforms, designed by New York fashion label Telfar. White Castle declined to release sales figures but says the test more than doubled sales goals; the chain is hoping to add more markets soon. Meanwhile, McDonald’s tells Fast Company that it is investigating the idea of selling a plant-based burger, and KFC announced that it’s working on vegetarian fried chicken, which it plans to start testing in the U.K. this year.