The maple bourbon ice cream from Clementine’s Naughty and Nice Creamery in St. Louis has all the flavor of bourbon without any of the boozy bitterness of an actual glass of bourbon. Yet, the alcohol is there. Clementine’s owner Tamara Keefe won’t say how she does it, but somehow, she makes ice cream that’s up to 18 percent ABV — that also tastes good. It took her about six months to develop a process for infusing alcohol into ice cream with the help of “people who were smarter than me,” and she’s filed a patent on the trade-secret process. “It’s been a huge game changer for us and for the industry,” she says.

It’s not uncommon for ice cream makers to flavor ice cream with alcohol — bourbon vanilla and rum raisin are two classic examples — but there are only a few ice cream shops that make booze a big part of their business. Boozy’s Creamery + Craft in San Antonio sells beer alongside ice cream, both infused with alcohol and with the option to add a shot to a scoop. New York City’s Ice & Vice has an “open bar” section on the menu. And Jeni’s Splendid Ice Creams, which sells pints around the country, has a four-flavor boozy collection. These ice cream purveyors don’t lead with the 21-plus nature of their offerings, but, as the name implies, Tipsy Scoop makes alcohol-infused ice cream exclusively. The brand has a flagship “Ice Cream “Barlour” in New York City, and it sells pints at retailers in New York, Massachusetts, Florida, Illinois, and Tennessee. Still, the cocktail-inspired flavors top out at 5 percent ABV, about the amount in a light beer.

At Clementine’s Creamery, Keefe makes both “naughty” (with alcohol) and “nice” (without) ice cream at a 5,000 square foot ice cream factory outside of St. Louis and sells it out of two Clementine’s Creamery ice cream shops. She has a third shop set to open in October, and is prepping her small batch microcreamery for major expansion.

Although Keefe made ice cream throughout her childhood with a hand-crank ice cream maker her family picked up at a garage sale, just five years ago, it wasn’t even a side business. But in 2014, she was feeling burnt out after months of travel, and a friend encouraged her to leave her corporate career and open the ice cream shop she always said she wanted in her neighborhood. She resigned weeks later.

Keefe began building her business at restaurants. She delivered thousands of pints to restaurant kitchens in the months before she opened up her first shop. “Part of my strategy was to go after high-end and cool restaurants because I knew they would be influential in my customer base,” Keefe says. Restaurants also gave her the inspiration for the boozy ice cream that sets Clementine’s apart from other rapidly expanding ice cream brands: One of Clementine’s restaurant clients asked Keefe if she could make an alcoholic version of her ice cream to put in his bar.

Here, Keefe’s former career proved useful: In her previous job in marketing, Keefe worked with product scientists and developers, so she reached out for help developing an actually boozy ice cream. “There’s been no innovation in ice cream ever. People are still making ice cream the same way they did 100 years ago,” she told them, and asked, “Is this possible? Can we figure it out?” They figured it out in time to open the first Clementine’s Creamery storefront in May 2015. The 500 square-foot shop at at the edge of historic Lafayette Square (Keefe’s own neighborhood) became the neighborhood ice cream shop she always wanted.

Flavors at Clementine’s change frequently, and adhere to a “cow to cone” philosophy, meaning the dairy cows that produce the cream for the Clementine’s ice cream are grass-fed and pasture-raised. “We’re starting out with this beautiful dairy product with this really high butter fat content. People aren’t used to eating ice cream like that anymore because they don’t make it like that anymore,” she says. The flavors, however, run the gamut from St. Louis-inspired gooey butter cake to pandan and grasshopper. Keefe also makes vegan options in crowd-pleasing flavors, like cashew salted caramel and coconut chocolate fudge.

It’s getting easier to find ice cream made with quality ingredients in adventurous flavors as brands like Salt & Straw, Van Leeuwen, Ample Hills, and others expand. Portland-based Salt & Straw, which made a name for itself with flavors like honey lavender and roasted strawberry honey balsamic with black pepper, opened its first shop in Portland in 2011. It’s since since grown to 15 locations in five cities on the west coast. Meanwhile, brands like New York City’s Van Leeuwen have grown with a combination of scoop shops and grocery store pints, a model pioneered by the original small-batch-to-$12-pint brand Jeni’s Splendid.

Clementine’s, with its unique approach to boozy flavors, could be the next name to appear on the national stage, but Keefe isn’t rushing to sell her ice cream in grocery stores, in part because she’s worried about lapses in food safety. (In 2015 a listeria outbreak cost Jeni’s Splendid $2.5 million in lost product.) “I’m highly confident we will explode, so I want to make sure we have the proper infrastructure in place,” she says.

Instead, like Salt & Straw, Clementine’s will grow with storefronts — 25 over the next five to seven years. Keefe plans to expand in and around St. Louis first. After the third Clementine’s Creamery opening this fall, she’ll open a few more in the St Louis area. And as soon as she has four or five ice cream shops up and running, Keefe says she’ll expand outside of Missouri. The plan is ambitious, but, Keefe already has a factory equipped to churn out large quantities of her patent-pending boozy ice cream (and the regular stuff, too). “I overbought from a size perspective so we can grow into it,” she says.

If the ubiquity of boozy milkshakes is any indication, there’s a market for spiked desserts. And if Keefe’s expansion goals come to fruition, going out for a cold pint may mean stopping by an ice cream shop.