Next month, Chicago’s Goose Island Beer Co. will release its latest Bourbon County Stout (BCS) expressions, which will include a double-barrel stout aged first in Elijah Craig 11-year-old barrels, then finished in Elijah Craig 12-year-old barrels. This collaboration between Goose Island and Elijah Craig’s owner, Heaven Hill Brands, is part of the growing phenomenon of brewer-distiller co-branding partnerships. Traditionally, brewers have sourced their Bourbon barrels from brokers, but the use of brand-specific barrels has created the ability to cross-promote with a specific Bourbon brand.

Goose Island’s barrel-sourcing agreement with Heaven Hill began four years ago as the company expanded its BCS line to include a Reserve variant—a stout aged in special barrels. In the past, Goose Island has also teamed up with Beam Suntory’s Knob Creek, using the brand’s 11-year-old Bourbon expression for its BCS Reserve. In addition to the 2019 Reserve, this year’s Bourbon County line will include a wheatwine ale, aged in Heaven Hill’s Larceny Bourbon barrels, and a reserve rye beer, aged in the distillery’s Rittenhouse rye whiskey barrels.

California craft brewer Anderson Valley Brewing Co. has partnered with Wild Turkey for seven years on its Barl series. Its Wild Turkey Bourbon barrel stout is available year-round, while its Huge Arker Russian imperial stout, Salted Caramel porter, and Old Fashioned brown ale—all aged in Wild Turkey Bourbon barrels—are released seasonally. “It’s been a great relationship,” says Anderson Valley brewmaster Fal Allen. The only challenge, he notes, is the 22-ounce bottle size, a package that’s been losing favor with consumers. Next year, the Barl series will likely be packaged in 500-ml. bottles.

Not surprisingly, brewers and distillers owned by the same parent company have also partnered on Bourbon-barrel aged stouts and other beers. Diageo Beer Co. released its experimental Guinness stout aged in Bulleit Bourbon barrels last year, as the first in a line of barrel-aged beers from the Guinness Open Gate Brewery & Barrel House in Baltimore. The limited-release beer was a Guinness Antwerpen stout that was brewed in Dublin and aged eight months in Bulleit barrels at the Baltimore brewery. Constellation Brands-owned Ballast Point Brewing Co., meanwhile, partners with sibling High West Distillery on the limited-release High West Barrel-Aged Victory at Sea imperial porter.

“Barrel-aged beers aren’t for everybody,” says Guinness brand director Nikhil Shah, explaining that last year’s barrel-aged Guinness was popular with beer drinkers who prefer a full-bodied beer and likely have a deeper appreciation for spirits. Goose Island educator Michael Smith notes that there’s already an overlap of consumers who drink Bourbon and barrel-aged beers, and that “when serious Bourbon drinkers see that a beer was aged in Elijah Craig barrels, their eyes light up.” And according to Heaven Hill master distiller Conor O’Driscoll, “Beer geeks tend to be whisk(e)y geeks, and vice-versa. Knowing about one of the products brings an interest in the other.”

Co-branded barrel-aged stouts are destined to grow in popularity, and new partnerships and expressions are a virtual certainty. “It’s safe to say that we’ll see another barrel-aged stout from the Open Gate brewery,” Shah says, noting that it’s possible brewers will start producing other beer styles aged in barrels from spirits such as Don Julio Tequila or Zacapa rum. Smith adds that last year’s BCS Reserve was “just the tip of the iceberg. We have some neat things planned for the next few years.”