Wendy’s Frosty’s is a beloved treat — and a new addition to the lineup will combine the familiar frozen dairy dessert with a beloved Girl Scout cookie.

Frosty’s have been a staple of the Wendy’s menu since the late 1960s when founder Dave Thomas decided to add a frozen treat to it. The drink has only grown in popularity. Last year, the chain served 500 per minute in the United States. The Frosty falls somewhere between soft serve and hard-packed ice cream, creating a frozen creamy treat that’s stood the test of time. 

For decades, just one flavor — chocolate — was available. In 2006, vanilla joined the lineup. In 2022, the fast-food chain started trying new limited-edition flavors. 

On Feb. 21, the fast food chain will start selling Thin Mint-flavored Frostys. Fans are excited about the idea, which will combine the smooth Frosty with the mint-chocolate-chip flavors of a Thin Mint, but designing the treat was harder than people may think. 

The cookie didn’t lend itself to a frozen treat, so the recipe had to be tweaked, according to John Li, Wendy’s Vice President of Research and Development. Instead of frozen pieces or chunks of cookie, Li and his team wound up developing a fudge-like cookie butter that can be swirled into a Frosty. 

The cookie butter adds the flavor of a Thin Mint but makes it possible for customers to still get their Frosty quickly. The way it’s swirled into the frozen treat ensures that customers get a taste of Thin Mint in every sip or bite. The swirl can be added to either chocolate or vanilla Frosty’s. Li said they initially thought about only offering one flavor, but decided that the swirl worked well in both. 

“You can’t get more nostalgic than a Wendy Frosty and the Girls Scouts,” said Li. “The fact that they’re coming together really pulls at the heartstrings of food lovers in this country.”