Nigella talks about cooking two chickens - one for now and one for later. If you cook two birds of the same size/weight at the same time, do you need to lengthen the cooking time, or is it the same as for one bird? Also, if you're cooking something savoury like a chicken, would you cook biscuits /cake at the same time in the oven, or will the flavours mix? Thanks, Jane
If cooking two chickens at the same time then the cooking time should be the same as for one chicken providing that the chickens are not crowded together in one small roasting pan and they are in the middle of the oven. If you have a slightly smaller oven this may not be possible in which case we would suggest putting each chicken in a small roasting tin of its own and then putting one in the upper half of the oven and one in the bottom half of the oven. Switch the chickens over halfway through the cooking time. After your calculated cooking time - which should be at 200c/400F 45 minutes per kg plus an extra 20 minutes or 20 minutes per pound plus an extra 20 minutes - check the chicken is cooked by inserting a thin, sharp knife into the thickest part of the thigh. If the juices running from the incision are clear then the chicken is cooked but if there are any spots of blood in the juices then put the chicken back in the oven for 10 minutes and check again.
If you have a good convection/fan oven then then maufacturers claim that you can cook several things at once as the oven is a constant temperature all the way through and you don't get a mixing of cooking odours. Unfortunately cakes and cookies generally bake at 180c/350F so the oven temepratures would not be compatible but some muffins and cupcakes can be baked at 200c/400F and the cooking time is fairly short so it is possible to bake at the same time as the chicken, though it is not something we would generally attempt. We would suggest that you check your manufacturer's handbook for more specific information about your oven.