Zach Koff, the chief operating officer of beloved and fast-growing burger chain Shake Shack, is well aware that Americans are increasingly health conscious and savvy about what they eat. Yet when it comes to a good, old-fashioned meal of a burger, fries and a shake, Koff believes that most folks will choose to part with their kale and quinoa and opt for an indulgent experience. That perspective, along with a focus on a high-quality ingredients and great taste, make up the core of Shake Shack’s business ph