In my mind, I've always grouped Illinois's horseshoe sandwich alongside Kentucky's famous hot brown. Both are open-face sandwiches so decadent you have to eat them with a fork, and both emerged during Prohibition to fill the booze-soaked bellies of late-night revelers. Check out this fun video on the sandwich from the Wall Street Journal.
Of course, when it comes to decadence, the roaring '20s ain't got nothing on today's cooks: restaurants in Springfield are engaged in an unofficial competition to see who can make the horseshoe eve unhealthier. Two words: deep fried.
I'd opt for the simplicity of the old-school horseshoe: an open-face sandwich featuring bread, ham, French fries, and cheese sauce. Originally, it also featured egg — yum. The sandwich gets its name from the horseshoe-shaped piece of ham and potato wedges that resemble nails. It's like a cross between the mornay sauce-covered hot brown and the famous French fry-laden sandwiches peddled at Primanti Brothers in Pittsburgh. A calorie bomb, to be sure, but worth trying for the historical significance, right?