Tigelle con lardo is the version where the fat goes in whole rather than pounded into a paste, and that single choice defines it. The tigella, properly the crescentina, is a small leavened disc cooked between the patterned plates of a tigelliera until pale and faintly freckled, then torn open along its equator while still hot. Into the warm seam goes a thin sheet of lardo, cured pork back fat, sliced so finely it is nearly translucent. Unlike cunza, the lard here is not seasoned, garlicked, and worked into a smear; it is intact cured fat that arrives as a sheet and melts on contact with the hot crumb into something silky, faintly sweet, and clean. The disc needs that melt to stop being plain bread, and the lardo needs the bread's heat and faint chew to keep a slick of soft fat from reading as merely greasy. The pleasure is the lardo dissolving into warm dough and almost nothing else.
The craft is in the slice and in temperature. Lardo must be cut paper-thin, because a thick coin sits cold and solid and never surrenders, whereas a near-transparent sheet collapses into the warm crumb the instant it touches it. The disc therefore has to come straight off the iron and be filled immediately; a cooled tigella leaves the fat firm and the build flat. Good lardo is itself the seasoning, cured with rosemary, pepper, or herbs in the rind, so a careful build adds nothing more and lets the cure carry the flavour. The restraint is the point: one thin sheet per disc, laid flat so it melts evenly, perhaps a single grind of pepper. A sloppy version uses thick slabs that stay waxy, overfills until the fat pools out the seam, or piles meat on top and buries the very ingredient the dish is named for.
The variations are the same warm split disc with a different thing meeting it, and each stands alone. There is the disc dressed with pounded cunza instead of whole lardo, the herb-and-garlic pesto modenese version, the one with prosciutto added over the fat, and the loaded salumi misti build. There is also lardo used the same way on warm gnocco fritto, a fried dough rather than a pressed one. Each swaps a single element while the iron and the seam hold constant, and each deserves its own article rather than being crowded in here.