The air itself smells rich and sweet. Hot ghee, sugar and roasted cashews, simmer together with wheat milk in many enormous iron kadais (vats). A master cook stands next to each one. With an iron ladle as tall as a man, he rolls back the liquid from the corners. Now and then, he turns up the mud stove’s heat: he adds a piece of wood and the fire leaps and crackles. The kadais get hotter, and the liquid hisses and boils and thickens to a dark orange. He then checks the consistency by rolling a blob between his thumb and forefinger. He stirs some more. When the ghee floats up, he decides it’s done. He pours it into cooling dishes and stacks them in the next room. A new batch of Tirunelveli Halwa is now ready to serve.

For the last 87 years, the halwa has been hand-made in the same room, says Jayalakshmi Srinivasan, 35, who runs Lakshmi Vilas, one of the oldest Tirunelveli Halwa shops in town. She is the fifth generation of her family to make this north Indian sweet that borrows half its name from a small town in Tamil Nadu. “The zamindar of Chokkampatti (a village near Courtallam falls, Tirunelveli district) went to Varanasi on a pilgrimage. There, he ate wheat halwa, loved it, and offered the Rajput cooks who made it a job in his palace kitchen. A few families came with him. Ours was one of them,” Srinivasan says, showing me a souvenir book with the store’s history. Besides their kitchen duties, the Rajput cooks also made sweets for festivals in nearby towns. Later, they sought the zamindar’s permission to move to Tirunelveli. He agreed. And so, in 1882, Srinivasan’s great-great-grandfather Thukaram Singh started Lala Kadai, which was probably Tirunelveli’s first halwa shop.

The word ‘halwa’ comes from halawa, an Arabic word for sweet, explains S Mallika Badrinath, culinary expert and author of 29 cookbooks. And the version from Tirunelveli is becoming hugely popular across India now and, ironically, for a halwa that came from the north and perfected its identity in the south, it is now returning to the north. The festive season is seeing a spurt in such orders. “We get some of our big orders from Dharavi’s Tamil community, and now, with Diwali, we have corporate bookings from Mumbai and Bangalore, enquiries from Delhi, and plenty of orders from Chennai,” says G Moses Dharma Balan, founder of Halwakadai.com.

A search for ‘Tirunelveli Halwa + buy + online’ fetches 61,500 results in 0.62 seconds. Balan tells me his was among the first websites to set up online shop, back in April 2014. Today there are plenty more—Tirunelvelihalwakadai.com, Sweetkhana.com, Sweetkadai.com —who have opened e-shops with the promise of delivery in under 72 hours across India.

Traditionally, in Tamil, halwa’s ‘h’ is dropped, and it is simply called ‘alwa’, explains Mallika Badrinath. Tirunelveli Halwa is also distinct from other wheat halwas in the way its prepared. "In Mumbai halwa is made with the milk squeezed from maida. Nowadays, I hear it’s even made using corn flour, because it’s faster. But the original Tirunelveli Halwa—which gets its colour from caramelized sugar—is a long, tedious process, and calls for great skill. It is nearly an art," concludes Badrinath.

If so, then it is clearly an art form that’s practiced all over Tirunelveli. Walking around town, I find more halwa shops than I could visit in one evening. All of them do brisk business; the famous ones have long, impatient queues. There is Iruttukadai (literally the ‘dark shop’ because the sweet is sold—since 1900 when it opened—only late in the evening), Santhi Sweets (which has many closely and confusingly named pretenders) and Lakshmi Vilas (as Lala Kadai is now called). There is little by way of advertisement. Yet, when friends learnt I was about to visit Tirunelveli, each mentioned a favourite shop and asked for a parcel. For a dish made with wheat—which the rice- loving South barely grows—it is in great demand.

“The samba wheat for our halwa comes from Mumbai,” explains Srinivasan. “The butter is sourced from Oddanchatram [a town not far from Kangeyam, famous for its native cattle], and, of course, we use water from the nearby Thamaraparani river.” Everybody—Srinivasan, her staff, the people of Tirunelveli, the internet— tells me that it’s the Thamaraparani’s water that gives the halwa its flavour. And while I believe them, I’m inclined to credit the laborious process of making the halwa equally.

It takes many man-hours and stages to convert wheat into halwa. First, the wheat is broken and soaked for 12 hours in —yes—Thamaraparani’s water. Then it is finely ground, the milk is squeezed out and is left to ferment (the leftover wheat mulch becomes cattle feed). The fermented wheat milk, 7.5 kg of it, is used to make a single batch of the sweet. It is slow cooked over a wood and cashew-husk fire. The husk, I’m told, lends a certain flavour.

Much of the halwa-making still remains as it used to be decades ago. Take the ghee: it’s melted inhouse; just as the butter begins to clarify, betel leaves or drumstick leaves are added (the leaves—you might have guessed— are also added for flavouring).

“Earlier, women used to grind the wheat on a rough granite mortar-and- pestle set into the ground,” explains Srinivasan. We’re standing next to the mechanised grinders—the one concession to modernity—inside the halwa room. It’s noisy and hot and hazy, with smoke climbing out of the kadais, and spreading the sweet aroma, the halwa heat and grease generously. Next to the heaving grinders, there are buckets of wheat soaking in water, and tall steel containers in which wheat milk ferments. To one corner, there are tins of ghee sitting in hot water, waiting for the fat to melt; there are jute sacks full of dried cashew husk; and mud- stoves with the last of the firewood fading from red to black. “It takes two and a half hours to make a batch,” Srinivasan tells me, leading me back to her office. In the cool and comfort of the room, just a two-minute walk from the factory, the rumble of the wet grinders, the constant stir and scratch of the six-foot iron ladles, and the men in lungis and vests, who have worked there for decades (one has clocked 43 years) seem far away.

For a sweet so famous, Tirunelveli Halwa isn’t all that expensive. A kilo retails between Rs 140 and Rs 160 (in store) and Rs 180 (online). It remains a budget sweet, one that can still be bought in small servings.

“I studied in Tirunelveli in the 1950s,” says Theodore Baskaran, a writer. “There was always a crowd around the halwa shops. At Irrutukadai, for two annas, they would serve a small piece of halwa on a plantain leaf.” They still serve it on a plantain leaf, he says, as he found out on a visit three years ago. “A small piece now costs Rs 5. But the shops are as crowded as ever.”

But the halwa has not just remained a popular sweet dish; the word itself has crept into colloquial Tamil. “There is a term, ‘halwa kodukaradhu’, it literally means ‘to give halwa’. But what it actually implies is giving someone the slip,” Baskaran explains. It is unclear if the term is a dig at the slippery nature of the sweet: try holding onto a piece served on a plantain leaf.

Tirunelveli Halwa appears in pop culture and cinema too, especially in film songs (‘Tirunelveli halwa da’ from Saamy, 2003), and is central to Tamil films’ romantic and comedy scenes; in the former, the husband usually presents a packet of halwa and a strand of jasmine to the wife, who goes all coy; in the latter, the comedian presents the same to another man’ s wife. Things do not go well for him.

In the early halwa days, there weren’t any shops. The sweet was taken around town and hawked. Srinivasan has heard stories in her own family: of her grandfather and his brothers coming home late at night and then cooking 20 kg of halwa for the next day’s sale.

At the factory, the cooled halwa is weighed and packed by a team of men. They have to keep the three Lakshmi Vilas shops in town —along with halwa lovers everywhere—well supplied. Their numbers show no decline, despite "Online stores, like ours, may not have a manufacturing unit. We buy the best from the big names in Tirunelveli and resell it," says Halwakadai’s Balan. "So many people advised me to start making it in Chennai, but the real halwa, made with Tamaraparani water, cannot be replicated."

But then, Tirunelveli Halwa is unique in taste and texture. Srinivasan offers me a melamine cup full, still warm from the kadai, glistening with desi ghee and studded with cashews. It’s delicious, and melt-in-the-mouth rich. But it is also a heavy sweet. Srinivasan’s son helps me polish it off.

Srinivasan’s family members still speak to one another in Urdu. Their family deity is a goddess from the village where it all began— Kalanganadi Amman, at the temple in Chokkampatti. The staff, all 70 of them, are from Tamil Nadu. “My son and daughter will be the sixth generation to run the business,” Srinivasan says.

In some ways, Tirunelveli Halwa’s journey—from north to south India— was only the beginning.