The Staffordshire oatcake with bacon is the oatcake's baseline filling, and the build is decided by a bread that is nothing like the biscuit sharing the name. The Staffordshire oatcake is a soft, floppy, savoury pancake of oatmeal, flour, and yeast, cooked thin on a hot griddle, pliable rather than crisp, closer to a Breton galette than to anything baked. Bacon is the load the oatcake was made to carry. The defining decision is the carrier: the oatcake bends completely around hot bacon and seals soft against itself instead of stacking between two rigid faces, and in the Potteries this is breakfast and it is regional before it is anything else.
The craft is heat, the order of assembly, and how the oatcake handles bacon fat. The oatcake is warmed through on a griddle or under a grill, because one left to cool turns leathery and splits when folded, which defeats the format. The bacon is cooked to render its fat and crisp its edge, then laid on while the surface is still soft enough to bend, usually with cheese melted under the grill so it grips the oat surface and binds the fold. The oat structure is sturdier than soft white under grease, so it soaks a little of the rendered fat without going to paste, taking on salt and savour as it does. It carries no separate sauce, because the oatcake's own faint, nutty, slightly sour flavour is part of the seasoning and a wet dressing would only steam it limp. Folded in half or rolled into a tube, it is engineered to be eaten in the hand off a hot plate rather than packed cold.
The variations stay inside the warm, folded frame. Bacon and cheese is the baseline; bacon with egg or with the full-breakfast load pushes it toward a complete meal in a single fold; a double oatcake stacks two with the filling between for a heavier build. The sausage version swaps the cure for a different savoury slab, and the Derbyshire oatcake is a close regional cousin with its own crumb and loyalties. Each deserves its own article rather than being crowded in here.