It's no secret that cocktail junkies have a thing for old-time imbibing. But lately, bartenders are bringing Little Italy to Don Draper-style drinks.

Amaro — a category of Italian bittersweet liqueurs dating back to the 1800s — has found its way into contemporary cocktail culture and stateside bartenders are infatuated with these herbal elixirs.

"The fact that young American bartenders have picked it up as their hot new thing is a little bit odd," said Marvel Bar mixing guru Pip Hanson. "It's a cultural artifact that's hard to get a solid grasp on for an American bartender unless they've really spent time in Italy."

In bruschetta country, amari (the plural for amaro) are commonly enjoyed straight as after-dinner sippers, though some are used as aperitifs with soda or tonic, said Eric Seed, an Edina wine and spirits importer, who is one of the semifinalists for best spirits professional for the James Beard Foundation awards. Through his company Haus Alpenz, Seed imports several amari, including the deep and dark Rabarbaro Zucca — a northern Italy staple made with rhubarb root.

"Part of the lore of the products is the feeling that they give as a digestif," Seed said. "They've historically been consumed to settle the stomach after a meal, even though there are no medicinal qualities."

Despite amaro's increased back-bar presence in recent years, Hanson and other amaro-enamored bartenders say it's somewhat of an elusive category. Unlike bourbon or tequila, amaro — Italian for "bitter" — is not a regulated classification, which leads to wide variations among producers and exponential subcategories often based on ingredients or regions. The free-range flavor palette ranges from rich, vegetal expressions such as Luxardo Amaro, to grappa-based Amaro Nonino's hints of caramel and orange.

Bartender Matthew Voss at the Marvel Bar.

"The field is so vast and we see so little of it," said Peder Schweigert, barman for Marvel, which is a semifinalist for outstanding bar program in the James Beard Foundation awards. "We might see one example of a given class, and not the depths of the field."

The scope of the potable bitters is even wider when accounting for other countries' pungent liqueurs, such as France's gentian-distilled Suze or Hungary's Zwack Unicum, with its licorice and chocolate notes. "[Amari] have the advantage of being a semi-definable category, but really they are part of this broad spectrum of ancient herbal liqueurs that little farmsteads have been making for centuries," Hanson said.

But it's not just base notes and geography that distinguish amari from one another. Sometimes the proof is, well, in the proof. Without a formal style definition, the booziness can vary greatly from product to product. While Cardamaro, a wine-based amaro made with cardoon and blessed thistle, checks in at 17 percent alcohol by volume, the hard-to-find Centerbe can notch up to 70 percent. However, most amari settle into the 16 to 35 percent range.

An amaro for anyone

"These guys can basically do what they want," said Alex Bachman, partner and head bartender at Chicago's Billy Sunday. "In some ways it can be frustrating to understand the spirits, but on the flip side the cool part about it is these guys can exercise more creative liberty than what you see in a lot of genres."

Since opening last year, Billy Sunday has become an amaro mecca, featuring more than 500 varieties, including 200-plus types of fernet — an amaro subset best known for the minty Fernet-Branca. While fernet and Cokes are huge in Argentina, a shot of Fernet-Branca became known as a bartender's handshake in San Francisco and the bracing, 169-year-old liqueur has since enjoyed a cult-like following among barkeeps.

Robb Jones of Saffron in Minneapolis and his spirit-savvy peers have found other uses for amaro. Perhaps the most obvious application is as a substitute for non-potable bitters, such as Angostura and Peychaud's. Not only does Jones make a mean ice cream of Cynar (amaro with artichoke flavor), but he likes to add a touch of the liqueur to Manhattans, while dialing back the sweet vermouth. "You get that cool bitterness and it also makes for a warmer drink," he said.

Veteran Twin Cities bartender Chad Larson said he often scraps the vermouth entirely in favor of Cardamaro, while Hanson points out that amari also work as sweetening agents in drinks like the modern classic Paper Plane (so modern it was named after the M.I.A. song). "The fact that you can use Nonino and Campari together as a substitute for sugar is kind of a clue to their dirty little secret, if I can call it that," he said. "What people don't seem to acknowledge about amari is that they're super-sweet."

Maybe Grandpa Sergio didn't have M.I.A. or your next Manhattan on his mind when sipping his after-dinner Averna. But the craft cocktail movement is just doing what it does best — experiment.

"What we are doing by appropriating amari and using it for our own purposes is kind of what we do as Americans," Hanson joked. "No respect for the constituent ingredient."

Michael Rietmulder writes about bars, beer and nightlife.