you also can do it at the fishing guild its kinda bugged atm.. but it goes verry slow.
theres a cooking spot area at the fishing guild you cant open the door of it but when you use your food on the range it will still cooks it.
( Found it out by my self ages ago ) ... its bugged + you get firemaking exp from it.
Up to you if you like cheating then go ahead you earn the firemaking xp from me
Ur a cool guy , Dave will fix it sooner or later if he reads this post from mine lol.