1. Allow the pan to cool before filling it with water and adding a dishwasher tablet or 1tbsp biological washing detergent. Biological detergent has enzymes that are specifically designed to tackle food-based stains, and they work just as well on burnt-on food residue.
2. Put the pan back on the hob and bring to the boil.
3. Leave to simmer for around 10min, and the burnt bits will simply lift away, leaving your pan as good as new
4. Repeat as necessary, then wash thoroughly as normal. You can also use this method for hob-safe roasting tins, too.