CHICAGO — The smell of freshly baked bread wafts through Hannah's Bretzel, a downtown restaurant where the ovens are lined with rows of pretzel bread loaves that are sold on their own and used to make sandwiches filled with hams, cheeses and other gourmet ingredients.

"It's just soft and salty," said customer Stephanie Klein, who ordered an Italian Parma ham sandwich on the bread during a recent lunch hour and visits about three times a month. "I'm big on a soft, good-tasting bread."

Twist this: Baking experts say pretzel bread — a cousin of the ubiquitously popular crispy, salted snack — is growing in popularity, popping up on menus and in sandwich orders from California bakeries to New York restaurants.

The centuries-old chewy German bread with its doughy consistency and salted crust is extremely trendy around the country, said Tom Vaccaro, senior director of baking and pastries at the Culinary Institute of America, where pretzels are taught in classes.

"It offers a lot of flavor components when you eat it," Vaccaro said. "For a lot of people it's in that comfort food zone."

So it wouldn't be that much of a jump for customers to order a pretzel bread sandwich, said Peter Reinhart, baking instructor at Johnson and Wales University in Charlotte, N.C.

"It's not something that's so out of the box that no one's heard of it," Reinhart said. "We know that pretzel goes well with mustard, so it makes a good base for a sandwich."

Florian Pfahler started Hannah's Bretzel (he says in his native Germany, pretzel is spelled with a "b") in 2004 and has two Chicago locations with plans for more. His goal is to bring pretzel bread from Germany to the United States and he said he has earned a loyal following.

"What I hear time and again is, 'This is a tasty sandwich,' " Pfahler said. "The pretzel bread tastes so good."

The restaurant also offers bragels (pretzel bagels) for morning sandwiches, pretzel-shaped pretzel bread and mini baguette-shaped pretzel bread for sandwiches.

Pretzel bread baking has been taken to the artisanal level at Prime Meats and Cafe Pedlar, both in Brooklyn, N.Y., where co-owner and co-chef Frank Castronovo said they use a family recipe from his wife's father. Cafe Pedlar offers pretzel braids, twists and knots. Diners can order a German white sausage served with a pretzel roll at Prime Meats.

"The recipe has gotten mass produced, manufactured and it came very far away from its true beginnings," Castronovo said. "We're doing them the way they were meant to be made."

Across the country, in California, Hans Rockenwagner sells pretzel baguettes and rolls along with burgers and sandwiches made on pretzel breads at his bakeries and cafes in Los Angeles, Santa Monica and Venice.

"If it's something you can do with pretzel bread, we do it," Rockenwagner said.

His bakeries sell pretzel bread sandwiches with ingredients like cranberry sauce and turkey breast, ham with provolone and salami with Parmesan, tomato, arugula and mustard.

"It's the earthiness, the softness and the chewiness of the pretzel," Rockenwagner said. "It can hold up to all those flavors without getting lost or too soggy or overpowering."

National restaurant chains have taken notice, too.

Pretzel bread is featured on the menu at more than 1,000 Blimpie restaurants in the U.S. as part of a turkey, bacon and cheddar sandwich, but customers can request any sandwich on the pretzel bread.

"It has been a raving success," said Kate Unger, vice president of marketing for Blimpie. "We know once we get that product into our customers' hands we can win them over."

Pretzel bread also has an appeal for diners looking for something different, said Vaccaro, with the Culinary Institute of America.