@O.M.Y. : while I'm all for tinkering, be aware that there exist electric cherry pitters as well :). There are also more elaborate and larger ones, with a more ergonomic plunger, that you might easier to adapt automation-wise.

@DrisheenColcannon : yup, that's completely normal. A popular way to reduce this (and other consequences - such as bursting - of heating up a mostly air-tight food container, which is what a typical kiełbasa is) is to simply make a couple of regular shallow incisions of the food's skin.

@Catija : there are flat "lids" composed of fine wire mesh intended specifically for this purpose ( example ).

@RossRidge : good point. It's plausible we're dealing with the same process, although your surprise that the cakes don't disintegrate is telling - they really don't absorb any of the egg's mass, they simply appear to be coated by it (the fact that they are probably less porous than your typical bread might be a contributing factor).

@rumtscho : my thoughts' exactly, although puffed rice does have a low density, so probably not a lot of hight-temp moisture needed to get it softer. Well, we'll see if someone comes up with a definitive answer, in some time I'll probably experiment with a partial egg dip/covering.