What is the best temperature to roast a spatchcock chicken?
I use a fairly high heat of 500F (260C) to render fat and crisp skin (after chicken has been air drying in the refrigerator overnight). Most of the time, for me, a whole chicken takes about an hour and 15 minutes.  Depending on size, a spatchcocked bird will take about an hour.  Use a thermometer to gauge your preferred doneness.