I have used steel wool and baking soda. Also glass cooktop cleaner works well but is more expensive than baking soda. The steel wool got off that nasty brown baked on gunk on the handles of my Pyrex. I know that some have been worried about steel wool scratching but I didn't find that to be true. Just scrub gently. If worried about scratching try baking soda and a good scrubber. That works well but requires more elbow grease than the steel wool or the stovetop glass cleaner.