Heat oven to 200C/180C fan/gas 6. Stuff the chicken with the preserved lemon, basil, and bay leaves. Place in a roasting tin, season inside and out, then rub garlic oil all over the skin. Roast in the oven for 1 hr, basting regularly.
Test if the chicken is cooked by pushing a skewer into the thigh – if the juices run clear, it’s done. Leave to rest somewhere warm for at least 15 mins, catching any resting juices.
To make the toasts, grill or toast the sliced gluten free ciabatta. Drizzle remaining garlic oil onto the toasts, then roughly spread over with a knife. Remove the preserved lemon from the chicken cavity, roughly chop and scatter over the toasts. Drizzle with more olive oil, if you like, and serve alongside the chicken to mop up all the juices.