It should be porcelain. Some oven cleaner should do it. Our glass or cerami top stove was a mess. Besides a scraper because it is flat, wife bought some class stove top cleaner and some polish. If your surface is porcelain then I would try the glass or ceramic? flat stove top cleaner. She used a bit of elbow grease or repetition but it came spotless. She got it from Lowes.
Scouring powder etc will just ruin it. Paint will burn and turn some real ugly shades where it doesn't burn from grease heat etc.
You can always buy another stove top from many places around Elkhart, salvage places and catalogues . Every one is changing to all electric and flat top surfaces. I heard or read of someone buying one for 49.00 or so.
