The best parts of a real grilled cheese are the golden brown, just-greasy-enough toasted bread and the totally molten cheesy core, and Five Guys does both right. They turn the bun inside-out so there's maximum white, spongy surface to get griddled; and the ample American cheese gets totally melty, nothing still semi-solid. What's more, almost all of Five Guys's toppings are free, some of which can contribute an awful lot to a sandwich. My recommendation: grilled onions and grilled mushrooms. Embedded in a pool of melted American between two halves up a griddled-up bun, they make for a pretty tasty sandwich—especially for under three bucks.