If someone put a cholent on a blech or platta that wasn’t yet fully cooked. Is it ossur to put on top of it a towel (on shabbos in a way that there is no problem of hatmana) because this might “speed up” the bishul. What about to put on top of it challas, could this also affect the bishul of the cholent.
If the food is not fully cooked, it is forbidden to add any cover than will speed up its cooking, and this can be a full Torah prohibition.
However, it is hard to believe that placing challos on top will have any effect.
See Shulchan Aruch 257:4; see also Shulchan Aruch 318:4 and Biur Halachah s.v. Shayach.