The logo on the carbonized Pompeiian bread

[Carlton Bach]

Maybe iof you plasced a terracotta stamp with the baker's mark on the bottom of the metal pan? It'd be cheaper to produce than raised metal (carve a wooden mold, slap clay on it), make pans exchangeable, and would produce the desired effect (sharp leettering).

I found a brass pan at the flea market last WE that lookes like a Pompeii find, so I'll give it a try one of these days.