Simmer with vinegar and water
BarKeepers Friend should work....most grocery stores
Hi Paz: What I use is a paste of vinegar and cream of tartar (the dry stuff). Make a paste and put it on the gunk. Let it sit for about 15 or 20 seconds and then scrape off with a plastic putty knife or one of those plastic scrubbies. You may have to do it a couple of times if the gunk is thick, but usually not. There is no smell and it is environmentally safe. Good luck.
GP66 is a great degreaser. You can spray and let sit 2 minutes, then wipe away.
Barkeeper's friend is also good but a bit abrasive.
Oven cleaner works
Bar keepers friend is amazing stuff for that.
Here is a good article https://www.cleanipedia.com/gb/kitchen-cleaning/how-to-remove-burnt-on-grease-from-ovens-and-pans.html
Try Bar Keeper's Friend, that should do the trick. Or TSP substitute mixed with water in a spray bottle.