If it's really burnt on it gong to be a hell of a job to remove.
I work as a kitchen porter , washer up, in a commercial kitchen so i get this all the time, the chef always gets the porridge stuck in the pan.
Put some washing powder ( The stuff you use for clothes in the washing machine) and water in the pan and put it on the hob to boil . That is how we clean burnt/ stuck on pans in a big kitchen. After a few mins to an hour boiling with detergent water the burnt on stuff will be loose enough to scrape off and scrub clean. This works for anything even burnt on curry ! Mind you one chef did burn a pan so badly it took me 3 lots of boiling to get it clean.