I read many recipes, particularly tray bake stuff, that says bung all the veg in with the chicken thighs for 35/45 mins. If you do that the thighs are no way cooked enough. They need a good hour/hour and a half or so to be lovely and cooked and crispy, but if you put the veg in at the same time the onions and other veg are burnt. Totally nothing to worry about, but I wish the recipes would be a bit more realistic. Slow roast the thighs for a good 45mins to hour then add the veg for a further 30-45 mins and all is perfect.