Stuff we saw online:
“Before cooking: Preheat oven. Place the chicken in ovenable bag in a deep roasting tin (approx. 5 cm deep). Cook for 1 hour on the middle shelf of the oven. Make sure the bag does not touch the oven walls, shelves or heating element. During cooking: Remove from the oven, place on a flat heatproof surface and open the bag carefully by slitting down the front of the bag with scissors. Take care when opening the bag as steam will be released. Baste the chicken with the cooking juices and return to the oven and cook for a further 20 minutes. Handle with care: The bag may open during cooking and cause cooking juices to seep from the foil tray into the roasting tin. ”
— from Sainsbury's 1.45kg Rotisserie Style Whole Chicken | Sainsbury's as of 26 October 2026