Below the dining area of Shake Shack's bustling West Village location sits a culinary laboratory constantly cooking up new ideas. 

The Innovation Kitchen, as it's known, is responsible for developing burgers, sandwiches and shakes that will be served both at home and at Shacks as far away as Bangkok, Thailand.

"Any of the new menu items that you see in any of our Shake Shacks all over the world have all been developed, researched, agonized over and tasted right here," John Karangis, executive chef and vice president of culinary development at Shake Shack, tells CNBC Make It. 

Shake Shack has nearly 350 locations in the U.S. and another 134 around the world and is valued at more than $4 billion. With dozens of new locations opening later this year, the team in the Innovation Kitchen is constantly developing new offerings. 

"Whenever we open a new Shake Shack we want to be incredibly thoughtful to the place or the neighborhood where we're going to be," Karangis says. "Our team will go out months or sometimes years in advance and do extensive research to understand what's really important to that place and those people and that culture." 

When Shake Shack opened its first Japan location, for example, the Innovation Kitchen's team flew 6,700 miles to Tokyo to explore the city's unique flavors. What resulted was the Shack-ura Shake, which featured cherry blossom jam mixed into the chain's famous vanilla custard. 

In order for a menu item to reach customers, it needs to be approved by Shake Shack's 13-person tasting panel. The panel evaluates everything ranging from the taste of food to the specific order in which ingredients are stacked on a burger bun. 

"We agonize over what additional supporting ingredients could go on it," Karangis says. "Should onions and pickles go on top or on the bottom? Everything really matters."

And it's not just the taste that needs to be taken into consideration. How delicious an item is is only one of the factors that the Innovation Kitchen team thinks about when developing new recipes. 

"We need to make sure we can market it in a way that can support our financial goals," Karangis says. "We need to make sure our teams in our Shacks can consistently execute it at a very high level. If one of those was to fail, we wouldn't be set up for success."

In the case of the Shack-ura Shake, the frozen treat proved to be a hit and made seasonal appearances in Japan each spring before eventually making the move stateside. 

Shake Shack's latest limited time offering — a barbeque inspired menu — was months in the making. Karangis and his team made "at least 25 different versions" of each of the new burgers before settling on the final "build" for the nationwide release. 

Though the Innovation Kitchen normally focuses on those limited releases, some items like avocado and crispy onions have graduated to being full-time mainstays on the core Shake Shack menu. 

Karangis likes passing by a Shake Shack when he's not in the kitchen and seeing if customers are enjoying the items his team developed. Once in a while, he says, he'll ask someone "How is that?"

"At the end of the day, our job is to make someone's day or their meal a little more enjoyable," he says. "It feels really good to know we accomplished that."

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