Costello’s Market is the only Vermont eatery north of Manchester that advertises in La Cucina Italiana magazine. But when you venture to the Middlebury establishment, don’t expect to see a mustachioed gentleman behind the counter yelling at his staff in Italian.

The fiftysomething owners of Costello’s, a longtime couple, know and love Italian food. They just can’t claim to carry ancestral memories of the old country in their bones: Both are of Irish descent. Carolyn Costello is part of an old Middlebury family. Her grandfather ran the town’s gas station in the 1930s; her uncle opened Bakery Lane Food Shop, where he prepared pies and cakes for decades. Her business and life partner, John Hamilton, grew up in an Irish-Italian neighborhood in Philadelphia. He says his love of food from the Boot was born early: “Since the Irish didn’t cook that great, that’s what we ate.”

While the staff of Costello’s may not embody Italian-market stereotypes, the food meets expectations and surpasses them. Hamilton, 53, has been cooking Italian fare for 40 years since he got his first job at an old-world bakery in his hometown, making bread and pasta. The experience shows in all his dishes, which range from traditional porchetta and homemade orechiette to meatball subs. He and Costello add new dishes to the menu after every trip to Italy (usually during their two-week break in November). Hamilton’s colorful culinary imagination contributes others. A large selection of specials changes daily.

Costello is quick to praise Hamilton’s unique palate, which inspires his flavorful takes on classics and generates unexpected, even downright weird, combinations. Last week, one popular special was a fried banana burrito. Besides bananas, the wrap contained local chèvre, roasted peppers, spinach and rice noodles. Another unusual dish: pasta tarts, in which Costello’s does a brisk business, especially around the holidays. The smoked-salmon tart features fish, spinach and bacon atop a crisp nest of fettuccine.

Most of the everyday business at Costello’s comes from Middlebury College students and retirees who live at the Marble Works Residences, a quick walk from the market. Seniors begin trickling in not long after the market’s 10 a.m. opening.

Some head straight for the fried frutti di mare. Black River Produce supplies Costello’s with local vegetables and fresh seafood daily, and it’s not out of the ordinary to see sushi-grade unagi or hamachi in the case. Hamilton makes his own crab cakes, and salmon poached in leeks and lemon.

At lunchtime, the market fills with Marble Works residents who have trekked through the snow for a from-scratch tuna melt topped with crackling, imported sharp provolone and a light dusting of parmesan, or a fish taco or oyster po’ boy. Costello says dinner, available from 3 to 6 p.m., is also popular with the market’s neighbors. They can make a quick meal of dishes such as seafood pasta with shrimp, scallops, calamari, fresh fish and lemon-basil butter; braised pork with mushrooms and onions over pappardelle; or herb-roasted duck leg with fennel and balsamic cippolini-onion glaze.

Last week, the market accommodated a slew of Midd kids who had been assigned to blog about their favorite places to eat in town. By noon, so many students were ordering salads and Italian subs that it was hard to navigate Costello’s network of counters. One young man, brandishing a notebook, inquired about the caffeine options — pour-your-own Seattle’s Best coffee and, to take home, beans imported from Italy.

Crowds are no rarity at Costello’s, which doesn’t have indoor seating. In the warm months, a few diners can occupy Adirondack chairs at an outdoor table Hamilton built himself and covered with flower-filled terra-cotta pots. During the summer, Costello says, “There’s lines out the door. Six o’clock at night we can get to the bathroom and drink a glass of water for the first time.”

Among the market’s student clientele, a particularly popular sandwich is the “Sicilian.” The 6-inch regular sandwich (yep, the large is bigger) is filled with three enormous meatballs stewed in Hamilton’s zippy “gravy” (tomato sauce) and sweetened with whole basil leaves and large chunks of onion. The meatballs would make your nonna jealous: super-soft, beautifully seasoned loaves that practically fall apart as you bite them. The same combination of cheeses from the tuna melt adds a creamy note to the dish.

Another dish thrills without any continental pedigree. Two years ago, Hamilton won the Middlebury Winter Carnival’s chili contest with a wonderful surprise — ground beef and beans stewed in red wine and chocolate. The stew misses none of the chile and cumin high notes of your average chili, but Hamilton adds tangy hints of red wine and creamy, earthy chocolate to the mix for a dazzling combination.

While Costello’s serves plenty of locals, aficionados of fine Italian food, drawn by those ads in La Cucina Italiana, have gone out of their way to try Hamilton’s dishes. The listing, says Costello, has brought fans from across the country. (The only other Vermont restaurant to have one is Al Ducci’s Italian Pantry in Manchester.) Costello recounts how one diner came for a second visit with about 20 friends, all wanting to eat Hamilton’s porchetta. “They bought two whole ones,” she says.

What exactly is porchetta? The classic Italian roast varies, but it’s often a whole pig — skin, fat and all — heavily salted, seasoned, rolled, tied and slow-cooked until it’s fall-apart tender. Hamilton describes the porchetta trucks that roam Italy’s roads selling sandwiches of sliced meat. “The big white truck pulls up, and they slice it for you plain,” he says.

Hamilton and Costello first tried porchetta in Umbria. “Just outside Rome is known for it, too, but we haven’t tried it there yet,” Hamilton says. “Mine is probably more like in Orvietto, between Umbria and Rome.”

One thing that sets his porchetta apart is an abundance of fennel. After rubbing a large, flattened pork roast with salt, cracked pepper, crushed garlic and sage, Hamilton sprinkles the meat with fennel seeds and precious fennel pollen, then places a jungle of the herb’s fronds across the roast and rolls it. The drippingly moist finished product has a strong anise flavor from the fennel, but sage and garlic also sing.

Hamilton’s method of smoking porchetta is unique, too. After he throws the roast beast in the extra-large oven, the chef fills a hotel pan with paper, egg cartons and apple wood. Then he sets it on fire and plops it beside the pork. Fruity smoke billows from the oven as if it were a fog machine. Slowly, it fills the whole store with the aroma of burning wood and rendering pork fat, overpowering even Hamilton’s intense gravy. This goes on for 10 hours.

When Hamilton slices a porchetta fresh out of the oven, it falls apart like pulled pork. He grabs one of his homemade rolls — flaky and crisp outside, soft as a cloud inside — and dips it in the deep pool of pan drippings. Into the bun go chunks of meat, with seasonings evenly distributed. After a second dip of the bun in the drippings, Hamilton closes the sandwich and slices it in two. No condiments, no cheese, no veggies. Just pure, porkgasmic taste.

Not everything Costello’s sells is made on the spot. Some customers ask for their porchetta on Vie de France sub rolls — a parbaked, frozen product that Hamilton finishes himself for crusty, warm bread. Imported meats, cheeses and other specialty products are also big business for the market. Fans of Hamilton’s porchetta may want to try finocchiona, or Tuscan fennel salami. Other hard-to-find Italian meats include hot and sweet coppa, guanciale and a prosciutto di Parma of such high quality that it retails for $28.95 a pound.

The lack of seating gives the market room for a rich array of imported and native goods. Local Castleton Crackers sit not far from Asian green-mustard powder. Hamilton’s own mostarda of fig, pear, dried cherry and apricot occupies one counter; others hold tins of anchovies, both real and made of chocolate, and about 60 varieties of wine from Italy and Vermont.

Costello’s closes Sunday and Monday to allow the couple time to relax. This is, after all, essentially Costello and Hamilton’s retirement job. Before the market opened on February 4, 2007, Hamilton was chef at the Huntington House in Rochester. Costello says he told her, “I can’t be behind a stove working the line, doing 250 heads a night, when I’m 60 years old.”

They discussed opening a small restaurant of their own, but, says Hamilton, “Small restaurants rarely make much money.” With no servers — just a dishwasher — the couple’s market has low overhead.

It’s still a high-energy enterprise. Hamilton turns out dishes at a hummingbird’s pace, while Costello provides the friendly customer service, handing over each sandwich or plate of pasta with a smile and a “Thanks for thinking of us today.”

Costello says Hamilton doesn’t always relax on his days off — he’s busy experimenting and prepping new dishes. “John’s just so creative,” she says. “He always tries new, different things. We always have the customer in mind so they don’t get bored with us.”

At an Italian market as rich in surprises as in tradition, there’s no danger of that.