Preheat the oven to 190°C.
Cut the onion into wedges, the aubergine into 3 slices (horizontally).
Line a large roasting dish with the aubergine and onion wedges. Season with salt and pepper, scatter some oregano on top and brush them with olive oil.
Mix the rub, then massage the chicken with this under the skin over the breast and the thighs, then all over the skin.
Cut the lemon in half. Put one half in the cavity together with one garlic clove, a bay leaf and the chilli pepper (cut in half for a more fiery version).
Cut the other half into 1cm thick rings and put these on top of the vegetables in the middle of the roasting dish.
Put the chicken on top of the lemon rings, then put the dish in the middle of the oven, and roast for 15 minutes.
Meanwhile, mince the garlic and cut the courgette into chunks.
Take the dish out of the oven, turn over the chicken and roast for another 15 minutes.
Take the dish out again, turn over the chicken again, so breast-side should facing upwards. Scatter the tomatoes around it together with the courgette. Crumble any leftover spiced butter together with the minced garlic .
Cover the dish with foil, turn down the temperature to 170°C and gently roast for about 1hour, depending on the weight of the chicken (follow the cooking instructions on the packaging)
After an hour, test the chicken alongside the thighs - poke them with a knife, if pink liquid comes out, it needs more cooking. If it’s clear, then it’s ready.
Rest the chicken for 10 minutes, covered, before serving.
Carve the chicken and serve with the vegetables and freshly chopped parsley.