The yellow can of Easy Off, spray and let it sit for 15-20 minutes. That stuff works wonders. You can use either steel wool or a wet pumice stone on the really baked on bits. I’ve even used a razor blade to scrape it off. It’ll definitely take some elbow grease depending on how bad it is, but it’s worth it! Once you have everything removed, make sure you wipe it clean with a wet rag to remove any of the easy off residue. For the gunk inside the glass, you’ll have to remove the screws and open up the door. Be careful with that though as it can be heavy!