One day earlier this year, Tom Gumpel left work feeling terrible. The head baker of Panera Bread—the Downton Abbey of fast food with a nice classy-to-trashy ratio—Gumpel had been tasked with coming up with a gluten-free product for the company to offer. But he’d failed. What’s more, he didn’t even know if success was possible. He didn’t know what to do next. He wasn’t even particularly interested in doing anything gluten free.