Dubbed as the Famous Star, the burger is available in 17 locations across Madrid, Barcelona and Valencia - according to Moving Mountains.
The burger comes with pickles, onion, tomato, lettuce, cheese, and sauce, and can be veganized by omitting both cheese and the sauce.
'Innovative and high-quality'
According to VegNews, Moving Mountains Founder Simeon Van der Molen said: "We are very proud to partner with a fast-food chain as prolific and forward-thinking as Carl's Jr. Integrating a burger that is not only plant-based, but also healthy, into a fast-food establishment is a significant step and is a real taste of what's to come for the future of food."
Van der Molen, who describes the company's mission as 'to make truly inspiring flexitarian dining available to everyone', added: "With The Moving Mountains Famous Star Burger, consumers now have more innovative and high-quality plant-based options than ever before to satisfy meat cravings when eating out without ever compromising on taste."