The borlengo is the thinnest bread in Italy that still counts as a sandwich, and its defining feature is that it is barely bread at all. A loose batter of flour, water, and a little salt is poured onto a hot, wide pan and swirled until it spreads to the edges in a sheet you can almost see light through, then cooked until it sets lacy and crisp. What goes on it is not a filling so much as a dressing: cunza, the Modenese paste of lard pounded with garlic, rosemary, and Parmigiano, brushed across the hot disc while it is still pliable, then the whole thing folded into quarters and eaten in the hand. The bread is engineered to be a vehicle for fat and herb, and almost nothing else belongs on it.
The craft is in the batter's looseness and the heat of the pan. A thicker mix gives a soft pancake, which is the wrong thing entirely; the borlengo wants to be poured thin enough that it crackles rather than bends, with brittle edges and a faintly chewy centre where it folds. The cunza is the whole point and is applied warm so the lard slackens into the hot surface and the rosemary perfumes the steam coming off it. Grated Parmigiano is scattered over the lard so it half-melts into the paste rather than sitting on top as a separate layer. The fold is structural as much as it is a serving choice, four layers of crisp sheet holding a thin film of fat together long enough to carry to the mouth. It is made to order at a stall or a festa table and eaten within a minute, because a borlengo that has sat goes leathery and the lard congeals.
The variations are narrow and stay in the Modenese hills: the strictly traditional version with only cunza and Parmigiano, and the looser modern habit of folding in prosciutto or a soft cheese, which purists in the area treat as a different snack rather than a borlengo. There is also the closely related crescentina and the fried gnocco that share the same lard-and-salume logic on a sturdier bread. Each of those deserves its own article rather than being crowded in here.