After meeting with them, Cooper did exactly that and changed the pizza. The elementary students are happier now.
Revolutionizing school lunches is hard work. Cooper wakes at 3:30 in morning, and arrives at the kitchen by 5 o'clock. She then puts in grueling 10-hour days that on some occasions extend late into the evening at PTA meetings.
And while she looks and acts like a chef, she often sounds like a political activist.
"Seven billion dollars for school food. Seven. That's all," Cooper said. "We spend 50 billion on diet ads, 120 billion on diet related illnesses and the war is costing us between $3 billion and $5 billion a week. If we took three weeks off the war we could double what we spend on kids' health for an entire year by feeding them better food."
That fiery rhetoric springs from the heart of a rebel. Cooper herself dropped out of high school and drifted as a teenager until she landed her first job in a kitchen in Telluride, Colo. Something clicked and she found her passion.
She went on to attend the Culinary Institute of America in New York. Over more than three decades as a chef, she catered banquets for 20,000 people, cooked on cruise ships and served as chef for the rich and famous, from Hillary Clinton to the Grateful Dead.
For Cooper, cooking has always been a great career. But now, it's a calling.
"I'm not a chef anymore, I'm a lunch lady and that's a good thing," Cooper said. "I want to bring a real professional look and feel and attitude to the people who are serving kids food."
And what makes this food different from what she used to cook?
"This is the most important food I could be making," she said. "I'm very proud of it."
Another obstacle for Cooper is that she has very little money -- roughly three-and-a-half dollars a day per child for breakfast and lunch. And 60 percent of that goes to labor and overhead.
"You're left with, at best case, with 60 cents to serve a nutritious, delicious meal to a kid of about 600 calories," Cooper explained. "That's why we have such, you know, bad food in most schools. Because there's so little money and we need to change it. It's a policy issue."
That's what brought her to Berkeley. Her salary is paid by the Chez Panisse Foundation, started by legendary chef Alice Waters. Waters' foundation is dedicated to teaching kids about healthy food -- from the garden to the lunch tray.
Another formidable "opponent" in Cooper's campaign is the cheap, fast and easy food just blocks away from the Berkeley Public High School. It's a fast food mecca with stores like McDonald's and Domino's Pizza that lure high school students who do not even consider eating in the cafeteria as an option.
"There are a ton of kids who that go to McDonald's," said high school student Natalie McClendon.
Students like Paul Moktan, who said cafeteria food tasted "heck of nasty," and when ABC News met him, was in search of pizza at Domino's or some Chinese food.
Finally, there are parents who think they've been doing the right thing by giving their kids stuff like chocolate milk.
"As far as I'm concerned, chocolate milk is soda in drag," Cooper says. "Most chocolate milk has more calories and sugar per ounce than soda. Just read the label."
She concedes, however, that at home, parents may not completely abandon chocolate milk from their children's diets.