Does anyone know if you could put a blech on a glasstop oven
No you can’t it will break. What I do is fill a huge full size heavy duty aluminum pan with water and then cover it with its own foil cover, it doesn’t work with plain foil because it is not strong enough. I heat up the water before shabbos and then leave it on “low”. The heat rising from the hot water is even hotter than a hot plate and all the food on it stays really, really hot. I even leave potato kugel overnight on it.
It is risky. If it gets too hot the glass can and will shatter. Its happened to me.
It may be possible, but I know number of people who cracked theirs. Better to use a hot plate.
You can buy a large but shallow aluminum pan with a flat lid that is specifically designed to cover all four burners on a standard sized-range. Google “K’deirah Blech” to find vendors.
In most cases its not a good idea and i know many people that used a blech on glass and it did crack. I have a glass top but the grates on it are very high so i can use a blech on it.
You have to make sure that you do not cover the entire stove top or it will crack.