You need a metal scraper like a wallpaper scraper. That gets the burnt on stuff off. I work in a pro kitchen where we do 1,000 meals a day ( +15 Kg of bacon & 10 Kg sausages every morning just for breakfast rolls!), one chef in particular has a well earned reputation as a 'burn on expert'. I've never had to throw a pan out yet. Some take 2 or 3 days 'in the soak' but they always come clean in the end. Remember our pans are 'Missionary cooking pots' the littlest ones are 2 L the largest are 125 L .