The thick-slice trend is less a specific sandwich than a presentation choice that has spread across many of them: bread cut far thicker than the usual sandwich slice, so the finished item is tall, pillowy, and visually dramatic. Cut a loaf of soft Japanese shokupan into slabs two or three times the normal thickness, fill it, and the cross section becomes a wall of white crumb framing a comparatively thin band of filling. It photographs well, which is much of why it exists, and it changes the eating experience in ways that are worth being honest about. This is a format applied to existing sandwiches, fruit, egg, cream, katsu, not a recipe of its own, and its merits depend entirely on whether the bread can carry the weight it is being asked to.
The craft question is bread-to-filling ratio, and the trend lives or dies on it. Very thick slices only work if the bread is exceptional: a high-hydration, milk-rich shokupan that stays tender and slightly springy at depth rather than turning into a dense doughy mass in the mouth. The slice has to be soft enough to compress as you bite so the filling and bread meet, because a thick slab of merely average bread eats dry and bready and buries whatever it contains. The filling has to be assertive enough, in flavor or in quantity, to register against so much crumb; a thin smear lost inside a tall slice is the central failure mode of the whole trend. A good one balances the drama with substance: superb bread that is tender all the way through, a filling generous and bold enough to hold its own, a cross section that is striking and also satisfying to eat. A sloppy one is all theatre: a towering slice of unremarkable bread with a token streak of filling, beautiful in a photograph and dull in the hand, dry where it should be plush. There is no separate bind here; the structural job is just the bread itself being good enough that its sheer volume is a pleasure rather than a chore.
That makes this a lens on the rest of the catalog rather than a member of it, and the variations are really other sandwiches viewed through it. Thick-cut fruit sando turns the cream-and-fruit cross section into a pastel slab; thick-cut katsu makes the cutlet look small against the bread and tests whether the pork can still carry it; thick-cut cream sando leans fully into softness on softness. Each of those is its own sandwich with its own logic that the thick slice merely reframes, and each deserves its own article rather than being crowded in here.