It's bound to happen... if anyone suggests oven cleaner, do not do it.
If you want some amusement value, go outside, take some oven cleaner
and spray it on a sheet of AL foil, quickly ball it up, and leave it
on a non flammable surface until the exothermic reaction starts it
smoking.

I've had some badly scorched sheets. A couple times i scrubbed them
with a stainless steel scrubby (love them!)... I've also "seasoned" a
few by coating with light oil and baking till black... like you would
cast iron. The problem with cookie sheets and scrubbing is that you
will micro scratch the sheet, which will likely make it a little more
prone to sticking.


good luck! (and learn to use parchement paper or foil on your sheets!

--
May no harm befall you,
flip
Ich habe keine Ahnung was das bedeutet, oder vielleicht doch?