The popular vegan burger is officially taking on fast food.

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We've been following the rise of the Impossible Burger from its origins as a promising vegan meat alternative to the darling of chefs like David Chang. It's "bleeding" quality and ability to fill in seamlessly for ground beef has impressed diners and allowed it, and its most direct competitor the Beyond Burger, to thrive in restaurants and grocery stores. Now the Impossible Burger is doing what some might have once thought impossible, but has become less and less improbable: hit the fast food market. White Castle, famous for it's mini-sized, eat-'em-by-the-bagful sliders is putting the Impossible Burger on the menu.

Starting April 12, diners in New York, New Jersey, and the Chicago area can find a vegan slider option at 140 of the burger chain's locations. The burger by itself will retail for $1.99 or can be purchased as part of a combo meal. According to a statement from Impossible Foods, the Impossible Burger is made with "water, wheat protein, potato protein and coconut oil," plus soy leghemoglobin which contains a protein called "heme" that, when cooked, breaks down like meat and releases the burger's signature "bloodlike" juices. As opposed to the thicker, denser Beyond Burgers, the Impossible Burger patty is typically thinner and more akin to a fast food, griddle-style patty. In other words, perfect for White Castle's small, square sliders.

The Impossible Burger's reach has mostly been in the fast-casual space up to this point. Chains like Umami Burger, Hopdoddy, and Fatburger have adopted it, while the company used a cash infusion to build a production facility. Even Disney Parks have picked up Impossible products.

Meanwhile, Beyond Burger could be the next fast food option that lures the meat-averse back into the fast food fold. It's CEO recently stated intentions to get the product into McDonald's and other quick-service chains. That's after it was launched in Whole Foods, made a deal with national restaurant distributor Sysco, and was picked up by TGI Friday's in the fastest "test to table" product launch in the restaurant's history. The McDonald's move would make sense as its international locations have recently added McVegan burgers to the menu.