When Town Hall Brewery won a gold medal at the Great American Beer Festival for Czar Jack — its Jack Frost imperial stout aged in a used Jack Daniels barrel — there wasn't even a category for barrel-aged beer at the competition. It was 2001, and few breweries were aging beer in barrels at the time.

The Minneapolis brewery was on the cusp of what would become a major trend in craft brewing. They're still at it, 22 years later, with what is arguably one of the region's best barrel-aging programs.

A move from the brewpub basement to a temperature-controlled warehouse has allowed Town Hall to significantly increase the number of barrels it produces and better control the aging process. The brewery's annual barrel-aged event — expanded to two weeks since the pandemic — has been going strong every February for nearly two decades.

Head brewer Mike Hoops first learned about barrel aging during a presentation on experimental processes at the Craft Brewers Conference. "When I first heard that this was something that was happening and was possible, the first question I asked myself was 'How do I do that?' " he said.

Hoops chose a Jack Daniels barrel because that's what he knew. "At the time I didn't really drink whiskey much. I didn't dislike it; it just wasn't part of my world. So, the first thing I thought of was Jack Daniels."

His barrel selection has since matured. He selectively seeks out distilleries to partner with, and travels to get the barrels he wants. "We realized that if we wanted the really good barrels then we had to get in the car and go get them," he said.

And then the multistep process of pairing beers with barrels begins. Knowing the product that was in the barrel helps determine what characteristics might be infused into the beer. It's not that simple, though. Because bottled spirits are blends of many barrels, what's in the bottle may not be what you get from a particular barrel. Each barrel is nosed to determine its individual character.

Next comes developing a recipe to fit the barrel. It's not simply a matter of making a beer and throwing it into a barrel. "The barrel is going to tell us what it is," Hoops said. "Now it's our job to figure out something to marry to it. It's like pairing food. What grabs you and how do you highlight it?"

The aging process has also matured since the early days. Space constraints used to limit Town Hall's aging time to around nine months. The new barrel house has given them the luxury of extending the maturation almost indefinitely — sometimes years.

"As we developed the barrel program, we got more flexibility. We could start picking and choosing based on what we thought was ready," Hoops said. They taste each barrel regularly to evaluate its progress. How do they know when it's ready? "The short answer to that question is when it tells us it's ready," Hoops said. "I know that's a cliché, but it's true."

The improved process has yielded improved beers. This year's offerings take what were already great beers and steps them up a notch. They are smoother, richer and more complex than in previous years.

The 100% Malted Rye Barrel spent two years in barrels that once held whiskey made from 100% malted rye from an artisan distillery in Kentucky. The malted rye gives the typically spicy rye whiskey a nutty roundness. The beer hits the nose with luscious caramel and vanilla. On the palate, the caramel and vanilla are joined by citrus and honey. Fermentation with Belgian yeast strains brings bushels of fruit, like dates and cherries. It's incredibly smooth for its high alcohol content. The mouthfeel is almost pillowy. There is a pleasant warming as it goes down and a touch of rye spice in the finish.

Reflecting back on the original, Double Czar Jack is a good example of multiple-barrel aging. Two batches of the beer are aged separately in bourbon barrels from different distilleries and then blended. The blend is then aged again in barrels from yet another distillery. It's then finished in Woodford Reserve Double Oaked barrels. The result is an extraordinarily complex and velvety imperial stout. This is a stout that has been aged in barrels, not barrels that have been put into a stout — the stout comes first. Bitter chocolate and black licorice lead off; marshmallow, vanilla and chocolate brownies come in as it sits. Hints of maple add additional subtle complexity.

Hoops doesn't just age beer in whiskey barrels. Wine Barrel Bruin is a Belgian bruin ale that's aged in red wine barrels. Wine and beer are perfectly melded — both can be perceived separately, but they are intermeshed. The aroma is almost stout-like with Tootsie Roll chocolate dominating but joined by a bit of fruit. The beer is super smooth on the tongue. The aromatic chocolate returns in the flavor, joined by dates, plums and a hint of minerality. The pepper and fruit of Belgian yeast strains is apparent underneath. A light tannic bite develops as the beer warms in the glass.

This is the first year that Town Hall will offer mixed-culture beers during Barrel-Aged Week. Mixed-culture beers are fermented with more than one species of yeast, including regular brewers yeast and wild strains that bring a characteristic funk. Cherry Orchard MC is a wine drinker's beer — or as Hoops calls it, an "I-don't-like-beer drinker's beer." Think dry, sparkling rosé. It's light and fizzy, but not totally without body. Aged on Montmorency cherries, it has the character of cherry pie — a little tart and a little sweet. The barnyard funkiness is present but subdued enough to let the cherry and beer shine through.

Barrel-Aged Week

When: Starts Feb. 13 at the brewery's main location, 1430 Washington Av. S., Mpls., townhallbrewery.com

What: Different beers are released each day of the two-week event. Advance sales of cans begin Feb. 2 on the Town Hall website.

Special event: The brewery is holding five-course barrel-aged pairing dinners on Feb. 14-15 at 6:30 p.m. Seating is very limited; check the website for availability.