They still wear sensible shoes, but the nation's lunch ladies are trading in their hair nets for chef toques as they undergo a gourmet makeover.

With the childhood obesity rates creating demand for healthier foods in schools, more attention is being placed on the culinary skills of those charged with preparing it. What good are fresh local produce and grass-fed beef, for example, if the lunchroom employees know how to make only canned vegetables and frozen fish sticks?

"It's more work to cook from scratch, no doubt," said Dawn Cordova, a longtime school cafeteria worker attending Denver Public Schools' first "scratch cooking" training this summer.

Cordova and about 40 other Denver lunch ladies spent three weeks mastering knife skills, baking and chopping fruits and vegetables for some of the school district's first salad bars.

Denver is among countless school systems in at least 24 states working to revive proper cooking techniques in its food service staff.

The city issued its 600 or so cafeteria employees white chefs' coats and hats and plans to have all its kitchen staff trained in basic knife skills within three years. Well-known area chefs visit for primers on food safety, chopping technique and making healthy food more appetizing to young diners (hint: kids prefer veggies cut into funky shapes, not boring carrot sticks).

It's serious work. School cafeterias are the front line in an effort to reduce childhood obesity as public health officials warn that nearly a third of American children and teens are now considered obese or overweight. First Lady Michelle Obama started a "Chefs Move to Schools" program in June to highlight the need for better cooks in schools, and she is urging Congress to pass legislation that calls for higher nutritional standards for school meals.

The Child Nutrition Bill would require more fruits, vegetables and whole grains and less fat and salt in school lunches and breakfasts, Obama wrote in an essay in Monday's edition of The Washington Post.

For lunch ladies seeking new skills, "boot camps" are booming from California to New York.

"Demand is so high we can barely keep up with it," said Kate Adamick, a school-food consultant from New York City who started "Cook For America" lunch lady boot camps four years ago. Her business is so swamped with requests that she's having a hard time even training new trainers to perform school-food cooking seminars.

More culinary schools are looking beyond hotels and fine restaurants to send their students, and professors, to K-12 cafeterias as well.

"You have some great cooks in school cafeterias, but just like a chef at any restaurant, you get in a rut of doing the same thing every day because it's convenient and it works. You think, 'We'll just make chicken nuggets again because it's easy and they'll eat it,'" said Michael McGreal, head of the culinary arts program at Joliet Junior College in Joliet, Ill.

McGreal works as a mentor to the food service department at Chicago Public Schools, sharing menu tips and ideas for getting more fresh food on school trays. Lunch ladies, he said, are eager to cook healthier once they learn how to do it.

"It's not any kind of crazy skill needed. They can turn around and do it tomorrow if we teach them," McGreal said.

Time is a big concern for lunch ladies charged with feeding balanced meals to hundreds of picky kids in as little as 20 minutes. The frenzied pace is blamed for the lunch-line horrors everyone remembers. Soggy vegetables. Canned fruit medleys. Rubbery pizza languishing under a hot lamp.

At the Denver boot camp, lunch ladies were urged to steam or blanch their vegetables in smaller batches, even in the middle of a lunch period, so that cooked vegetables go "crate to kid" in 30 minutes or less. Instructor Beth Schwisow told the ladies that every batch of their vegetables is auditioning for a kid's plate, so it's crucial the veggies taste and look good. Schwisow looked slowly around the room and dropped her voice.

"You've got gray, mushy broccoli out? They take a bite of that, and they may never eat broccoli again. Ever. Their whole lives," Schwisow said, her eyes wide.

Several lunch ladies in the audience nodded solemnly.

Another obstacle? Cafeterias themselves.

Chefs say that schools embraced processed food so completely that many newer cafeterias lack the basics of a production kitchen, such as produce sinks, oven hoods or enough cold storage to keep meat and produce fresh.

"If we want to reintroduce raw meat, fresh fruit, we have to be able to handle all of it," said Jeremy West, head of food services for a school district in Weld County, Colo. West attended a recent boot camp and plans to start his own next summer for workers in his 28 school cafeterias.

In Boulder County, Colo., cafeteria workers and parents raised $500,000 last year through grocery-store donations and restaurant fundraisers to buy better kitchen equipment. The school system bought uniforms for the cafeteria workers and added training.

"Any school district that is trying to make significant change about what they serve kids, they have to look at the kitchens and the people working in those kitchens," said Ann Cooper, self-described "Renegade Lunch Lady" and director of Boulder County's nutrition services.

At Denver's boot camp, the lunch ladies were all smiles as they shouted encouragement to each other during a competition to create fancy fruit garnishes.

"We used to cook this way a long time ago, and I think it's great," said Marlene Camdelaria, a high school cafeteria manager who was carving a swan out of a green apple. "I have no idea why we went to all the processed stuff. This is so much better."