Chop the onions so they are rings and spread over an oven tray/dish (I’ll probably use tin foil for fear of bonding food to tray).
Sprinkle some sugar, honey and chilli flakes over them
I went with chili oil rather than flakes, but sounds like a good plan.
Mix them up well to get them fully coated.
You could use white sugar of course, but I use the brown crystallised ones because demerara.🤩
The pan is indeed a nightmare to clean, so might be worth tinfoil or paper, though it may just weld itself to that instead.
Think it was 200c, but hard to tell as the oven was rammed with sausages, chips and Yorkshires so hard the tell.
The key, and slightly tedious, thing is that you need to check them every few minutes and remove them as they go brown. For some reason they always take differing time to cook, so you need to scoop the ready ones out and put the rest back in again, otherwise you end up with some perfect and the rest either mushy pale or burnt to ****.