Now that the Impossible Burger is easier to find thanks to an increased production capacity, it's likely we'll see it at more fast-food places than ever. That's a good thing for both its parent company as well as those of us who could stand to eat a little less red meat. Popular fast-food joint White Castle is now serving the "Impossible Slider" at 140 different restaurants in New York, New Jersey and Chicago, and claims that it is the largest single restaurant group to serve the Impossible Burger.