Lunchables currently has an 84 percent share of the market for kids’ “combination lunches,” and its dominance, Guidotti said, is sustained by its meat-cheese-and-cracker boxes, which remain the best-selling and longest-running Lunchables product. (Its pizza meals are popular as well.) In the past few years, the brand has made forays into trendier realms, launching some organic options and, more recently, an “Around the World” line that includes an Asian Style BBQ Chicken box and Mexican Style Chicken Tacos.

Last year, Kraft Heinz sold $1.36 billion of Lunchables, according to Robert Moskow, a senior equity analyst at the investment bank Credit Suisse who follows the food industry closely. “That is up 19 percent over a three-year time horizon,” Moskow told me. “In the packaged-food world, that’s a home run, especially for an established business.”

Moskow attributes some of this recent success to how Kraft Heinz has positioned Lunchables lately. "If you think about the last 10 years, I think Lunchables had some fallow periods when it was trying to create a healthier version of itself,” he told me, adding, “I think lately it has gone back to its indulgent positioning, which, for better or for worse, that's what the consumer wants.”

Lunchables has tried healthier options in the past, with occasionally disappointing results. In the mid-2000s, a line that substituted yogurt for candy was introduced and then discontinued due to weak sales. And in 2011, the company started selling Lunchables With Fruit, but that is now defunct too. In Lunchables’ earliest days, its product-development team experimented with including apple slices and carrots, but scrapped the idea after seeing that the produce did not ship and store well.

When I asked Guidotti whether sales of Lunchables lagged as the company made its offerings healthier, he said, “We are not seeing this. Lunchables continues to grow household penetration and dollar sales.”

Whatever the effect of Lunchables’ nutrition experiments, the brand’s reign remains unchallenged. Andrew Ruis, a researcher at the University of Wisconsin at Madison and the author of Eating to Learn, Learning to Eat: The Origins of School Lunch in the United States, thinks the product has done so well because of how it fits into families’ days. “From a parent’s standpoint, you’re trying to assume all these different roles when you’re putting together a kid’s lunch,” he says. “You’re trying to assume the role of nutritionist; and the role of a chef; and the role of an entertainer, almost; or a psychologist, someone who can get into the head of your kid and know what they want and like.” Ruis says the idea that “it’s everything in one package, that all you have to do is purchase this thing” is powerful for parents who can spare a couple of extra dollars.