A big part of White Castle's appeal is the simplicity of their burgers: thin, tiny sliders — just beef, bun, onions, and a pickle — that can be eaten by the sackful. That's not to say the chain has shied away from innovation: White Castle was the first major chain to launch Impossible burgers. But for their latest new products, White Castle is taking a step forward by taking a look back: a more robust 1921 Slider and a new Creme Soda variety of Coca-Cola.

The burger – which is named the 1921 Slider after the year the chain was launched – is touted as White Castle's "most significant product innovation since adding a slice of cheese to its Sliders in 1962." And yet, this "new" burger is actually intended to replicate some of the qualities of White Castle's original 1921 burger.

First, the beef patty is thicker and round, similar to the smashed meatballs that inspired the brand's first patties. (White Castle switched to square patties back in 1954 to maximize griddle space.) Second, the burger comes topped with cheddar cheese, grilled caramelized onions, pickles, and — gasp! — lettuce and a slice of Roma tomato. Yes, this is a slider with all the fixins.

The new permanent menu item was tested last year in Cincinnati, followed by similar trials in places like St. Louis, Nashville, and Louisville. This week, it's being rolled out nationwide — with the sole exception of New York which won't see the burger until June.

"The 1921 Slider brings our menu full circle to the hamburger that started it all," Lynn Blashford, White Castle's chief marketing officer, stated. "Although we've made a lot of updates over 10 decades, the all-new 1921 Slider comes as close as ever to that very first slider with a few new twists."

White Castle is also adding another new menu item that feels like a blast from the past: Coca-Cola Crème Soda, which is arriving exclusively at White Castle before potentially seeing a to-be-determined larger release.

The new drink — which is described as the classic Coke flavor paired with just the right amount of rich creme soda — plays into the whole White Castle 1921 theme: Not only was Coca-Cola the only drink on the menu when the chain first opened, this new flavor was specifically built to pair with the new burger by creating a nostalgic mix. And, interestingly enough, Coca-Cola says that data from their Freestyle machines at White Castle show the customers already have an affinity for creme soda compared to customers at other chains.

"My great-grandfather came up with many brilliant ideas as he launched White Castle in 1921 and in the decades to follow," Lisa Ingram, the company's CEO, added. "Thanks to him, innovation has been part of our DNA from the very beginning, and he would be so pleased to see that our team members' drive to innovate is as strong as ever."