Cleaning help made a hot coffee and dunked her trief pastry inside. Do I need to kasher it? If yes, how do I do that? Tizke lmitzvos
My assumption is that the coffee was not made in the actual cup, but was boiled in a different utensil and poured into the cup. Additionally the coffee most probably had milk added to it, therefore it is a kli sheini, and the trief pastry did not make the cup treif.