I have a hot plate type device. I have put parchment paper on top, and pet food on top of that. I guess the metal of the hot plate can still go through the parchment paper and get into the food. I was curious if this is true or not.
The hot plate is stainless steel, so it's not supposed to be damaging, but I am wary of stainless anyway. I can taste when my food has been in stainless.
I am also avoiding aluminum foil. If I use a small pan, it will take longer to heat and need more clean up.