The Camembert sandwich is defined by the ooze problem. Camembert is a soft-ripened cheese with a bloomy rind and an interior that runs from firm and chalky when young to almost liquid when ripe, and unlike a firm cheese it does not hold a clean edge between bread. The whole sandwich is a negotiation with that behaviour: ripe enough and it spreads and seeps into the crumb and bleeds out the sides under any pressure; under-ripe and it is dense and tasteless and there is no point making it at all. Camembert warmed or baked compounds the issue, turning the inside fully molten, which is why the sandwich is so often built around heat that is then controlled rather than avoided.
The craft is managing flow and bringing in something to cut a rich, mushroomy, slightly ammoniated cheese. The rind is kept on because it is the structural skin that holds the soft interior together and contributes most of the savour; the cheese is sliced just thick enough to have presence without flooding, and sealed off the bread with butter so the seep meets fat rather than going straight into the crumb. Camembert is rich and one-note on its own, so it wants an acid or a sweet-sharp counter, cranberry, a fruit chutney, or thin apple, applied in a measured stripe that lifts it without drowning a delicate cheese. When the sandwich is toasted or the cheese is baked first, the bread has to be firm enough to act as a wall for a now-liquid centre, which is the same containment problem the toastie solves at a different temperature.
The variations stay on the soft-ripened shelf and the warm-cheese logic around it. Baked Camembert torn into a roll is the molten, dipping-bread reading; Camembert with cranberry is the sharp-sweet seasonal version; Camembert with caramelised onion trades acid for a deep savoury sweetness against the rind. Brie, its milder, less assertive relative, runs the same ooze problem with the volume turned down. Each of those is its own build and its own article rather than being crowded in here.