Few meals are as easy or cost-effective to slap together as a peanut butter and jelly sandwich. Nonetheless, JM Smucker Co. is reaping the rewards of shaving a few seconds off the process.

The company, which acquired the Uncrustables brand in 1999 for about a million dollars, is ramping up production of the frozen, crustless, circular sandwiches. Sales have grown rapidly, despite no real advertising or promotion, Smucker Chief Executive Officer Mark Smucker said in an interview on Wednesday.

“We have done virtually no marketing on Uncrustables,” he said. That’s because “until recently, we could not make enough.” Smucker is remedying the production shortfall with a new factory, and a third will begin operating in the coming years. It expects the business to soon reach a billion dollars in annual revenue.

The company, already a major seller of peanut butter and jelly, is going to increase advertising for Uncrustables as output rises, and it expects the products’ presence in schools to grow. They will also appear in convenience-store refrigerators, now that the company has formulated a new bread that allows the sandwich to last for five days in the fridge after thawing. The bread doesn’t have preservatives, Smucker said.

Uncrustables sales were about $650 million in the fiscal year ended April 30, from $511 million the previous year. That’s in spite of a price tag that is significantly higher than a regular, homemade sandwich and higher rates of inflation that have caused consumers to cut back on purchases. Smucker said Uncrustables’ popularity is due to its convenience and lack of mess.

While Uncrustables started in schools, they fall into the “ultraprocessed” category, a kind of food that health professionals are increasingly blaming for a range of problems. The standard peanut butter and grape jelly Uncrustables sandwich has 8 grams of added sugar. Bonnie Liebman, director of nutrition at the Center for Science in the Public Interest, says that’s about 17% of the recommended daily dose of added sugars, with only 5% of the protein. That’s “far from ideal,” she said.

Medical studies point to overconsumption of these kinds of foods as potential drivers of cardiovascular disease, diabetes, even death. While food companies were able to respond to low-fat or low-sugar diet trends with corresponding products, the ultraprocessed label may be harder to escape.

The lower-sugar version has 5 grams of added sugar, but they’re currently unavailable. Smucker said they’ll be returning to distribution. “Fundamentally what we want to do is make sure we provide options for the consumer,” he said.