The horseshoe is a sandwich that gives up the second slice of bread and then buries the first one. Thick toast becomes the base for a layer of meat, a heap of French fries piled on top, and a flood of cheese sauce poured over the whole thing, eaten with a knife and fork. The cheese sauce is the defining component, not the meat. It is what binds a loose architecture of toast, protein, and fries into a single plate, and the sandwich is named for the horseshoe shape the cut of meat traditionally made on the bread.
The craft is in keeping the base from dissolving and the sauce from breaking. The toast is griddled or toasted firm, often a sturdy slice, because it has to take the weight of fries and a ladle of sauce without turning to paste before the fork reaches the bottom. The meat is the variable middle layer: a hamburger patty, ham, fried chicken, or whatever the kitchen runs. The fries go on hot so they stay crisp at the edges as long as possible against the sauce soaking up from underneath. The cheese sauce itself is the real test, a smooth Welsh-rarebit-style sauce in the older versions, beer and sharp cheese cooked to a pourable consistency that has to stay glossy and not split under heat. Timing decides everything: served slow, the fries go limp and the toast is gone before the meal is over.
The variations stay inside the same open-faced, knife-and-fork logic. The ponyshoe is the same build at half size, a single slice and a smaller pile for a lighter order. Beyond Springfield, the impulse runs through the Louisville Hot Brown, which puts turkey and bacon under a Mornay and a broiler, and the St. Louis slinger, which buries eggs and meat under chili rather than cheese. Each of those is a codified regional build with its own rules and its own town behind it, and each deserves its own article rather than being crowded in here.