About four years ago, Atlanta author Cynthia Graubart stopped in for tea with her old colleague Nathalie Dupree in Charleston. Dupree, the Southern-food diva, cooking-show personality and author of 11 books, was in distress. Her magnum opus was turning into magnum hopeless.

Under contract to write the book of her lifetime, “Mastering the Art of Southern Cooking” (Gibbs Smith, $45), a volume that cheekily evokes Julia Child’s famous tome on French food, the former Atlantan was on the verge of returning her advance to her publisher, Graubart recalls.

For this formidable project, the grand dame of Southern cookery had spent two years collecting hundreds of recipes from Colonial days to the present. But she couldn’t get her unwieldy notes on peach pies, pot roast and pecan brittle into a cohesive ball of dough.

As it turned out, Graubart, a former television journalist who produced Dupree’s first three PBS series starting in 1985, was the perfect person to help. She organized. She structured. She tested recipes. “She was my full partner in this,” Dupree says of Graubart. “She knows how I work and how I think.”

From the clutter, these culinary co-authors pieced together what is being hailed as one of 2012’s top cookbooks, garnering praise from The Washington Post, The Chicago Tribune, NPR and The Atlanta Journal-Constitution’s John Kessler.

“Mastering” is a 720-page compendium of essays on Southern ingredients and techniques. It is stuffed like a fat turkey with Dupree’s delightful anecdotes on everything from Margaret Lupo’s deep-fried okra at Mary Mac’s to former Georgia first lady Betty Talmadge’s famous parties at her Lovejoy plantation.

“She always had pigs and chickens, freshly scrubbed it seemed, in the front yard with bows tied around their necks to greet her guests,” Dupree writes of Talmadge, who was married and later divorced from Herman Talmadge, who had been governor and U.S. senator.

The hardest part of Dupree and Graubart’s four-year collaboration may have been the cuts, taking 1,000 recipes down to 750 while preserving the prose that Savannah cookbook author Damon Fowler refers to as “vintage Nathalie.”

“It was a behemoth that she sort of wrestled with,” says Atlanta cookbook author Virginia Willis, a colleague. “But Nathalie really does have this fierce determination about what she does.”

“You should see the boxes and boxes I have of drafts and corrections and what-have-you,” says Graubart, who lives in Dunwoody with her husband Cliff, a rare-book dealer. In assembling Dupree’s musings on everything from Fish Muddle, a stew she calls Southern bouillabaisse, to the origins of the casserole, they discovered they had material enough for a breakout book — on biscuits. Like an appetizer before the main course, “Southern Biscuits” (Gibbs Smith, $24.99) — with about 90 recipes for the Southern staple — was published last year.

In “Mastering the Art of Southern Cooking,” Dupree, who grew up in Virginia, writes about her first meeting with Child. It was 1971, and Dupree was taking a final exam at Le Cordon Bleu in London. The young American chef asked Child what she should do with her life, and Child told her to start a culinary academy. In the mid-’70s, Dupree did just that, opening a cooking school at the old Rich’s department store downtown. The school led to her first PBS series, “New Southern Cooking.” She went on to host more than 300 television shows and specials that have been shown on PBS, Food Network and The Learning Channel.

One good question is why Dupree — who won James Beard Awards for her books “Nathalie Dupree’s Southern Memories” and “Nathalie Dupree’s Comfortable Entertaining” — would deign to write a definitive Southern cooking manual. The labor of love weighs about as much as a baby: 6 pounds, 4 ounces.

“I just wanted people to understand that Southern cooking spanned a long period of time,” says Dupree, who moved to Charleston 10 years ago to be with her husband, Jack Bass. “That it was really the mother cuisine of American cooking, and that’s why it’s here to stay.”

Asked if she plans to write another book, Dupree replied, “I’ve written a memoir, but it’s not very good.”