I usually soak a paper towel in water and let it sit awhile you could add some Dawn Power Dissolve to the paper towel if it's really bad. This usually works for me and loosens the burnt food. Good luck.

We have burnt on stains on our glass cooktop (ceramic?) ever other day. We also use the razor blade/cooktop cleaner method. Be careful about using other scouring powders because most or all will damage your cooktop. The only drawback to cooktop cleaners is that they require a lot of elbow grease. They get there eventually if you rub long enough. I have read that a magic eraser pad works but I haven't tried one.

I use Weimans (the one that is lotion-like and says heavy duty, not the every day spray) and very occasionally need the blade product made for glass topped stoves. Nothings burned onto this one that hasn't come off - and by my estimate its 12 yrs. 4 of them mine. Jenn Air, white glass. I don't ever cook again over a burned or cooking mark though, I begin with it clean each time I use it. Little bit of a pain, but I didn't buy the stove, a downdraft that went into the kitchen when someone else updated.

Mr. Clean Magic Eraser will polish off the last of it after you get rid of the thicker layers. I had a Tupperware bowl melt on to my glass stovetop and though I was doomed. But with perseverance I got is all off and toned my arms at the same time.

Use a knife that holds a single sided razor blade to scrape off most of the food. Make sure you wet the surface first to reduce the chance of scratching the glass and hold the blade so it runs close to parallel to the glass, not upright. You don't want to gouge the glass or scratch it but if you keep the surface wet and keep the blade parallel to the surface you can use quite a bit of pressure on the blade without any worries.

After you get most of the baked on food loosened from the surface, you can use a Magic Eraser to remove the rest of it. You'll need to rub quite hard in some cases to remove what is still left.

If there is grease on the top after using the Magic Eraser you can use a chemical designed to remove the remaining grease.

Once all the grease is removed and if the cooktop is black and you want it to look its very best then lightly spray it with a glass cleaner and buff it dry using a very dry microfiber cloth. Keep wiping until completely dry and you'll get a streak free glossy finish that looks like new! This step works well but only if you get all the grease removed, otherwise the grease will streak as you're drying the glass cleaner.

Hope this helps you.