Scrape first then scrub with a degreaser and a scratch free sponge like ScrubDaddy.
I have used a baking soda paste, just let it sit and then use a scratch free sponge to remove, repeat if needed.
For my white porcelian
For my white stove top I use a spritz of oven cleaner- only let it set for a few minutes . Spray just on the spots not the entire thing- at close range. After canning around the burners it gets bad.. I usually have to do it 2-3 times to get every bit. Be careful and cover the plug area with paper towels good. SO NOT to get the spray inside of there.. It wipes off easily.. WEAR Gloves and wipe down well after..
Razor blade scra it off then can use ho water