Oooo, I have burnt a couple of saucepans or thrice in my jam and chutney making, and the best thing I found is bicarb soda. But my method is to put in about half a cup full, then a cup or so of water and bring it to the boil. Once boiling turn the heat off and let it cool down. I’ve rescued my favourite two saucepans and a frying pan using this method.