This is one of my two favorite burgers in the world (the other is at Kuma's Corner, also in Chicago) and a borderline HOF dish. Au Cheval is renowned for their thin patties and a single is actually a double stack. Their grill is seasoned from years of cooking delicious beef and it imparts an incomparable flavor into the patties. The beef is coated in a perfectly melted American cheese and i got it topped with a fried egg and slab bacon. The thick, crispy yet tender bacon alone is worth the price of admission, as is the brioche bun everything sits on. Every aspect of the burger is executed so well. Au Cheval has a couple other high end bar food items on the menu like fried chicken and french fries, both of which are exceptional, as well as a wide range of beers. No reservations and lines here are crazy. Our group waited three hours, but the good news is Au Cheval is in an awesome neighborhood and there are tons of cool places to hit while waiting. We timed things right, so we put our name in, bar hopped and grabbed a smaller bite elsewhere, then went to Au Cheval for a big meal when it was our time.