Process for etching a pattern on a surface (S) of a sandwich roll or bun (P) after the roll or bun (P) has been baked, by applying to the surface of the roll or bun (P) a laser beam emitted from an etching unit (2) equipped with a laser source (20), said process implementing the following steps: focusing the laser beam output from the etching unit (2) with an adjustable focal length between the exit of the etching unit (2) and a focal point (PF) of the laser beam； adjusting the focal length of the laser beam so that the surface (S) of the roll or bun (P) to be etched does not coincide with the focal point (PF)； passing the laser beam over the surface (S) of the roll or bun (P) to be etched in order to produce the etch lines of the pattern, with a plurality of passes of the laser beam over each etch line； and placing the roll or bun (P) in a sealed package after etching.
