Preheat the oven to 180 degrees
In a large bowl, toss the aubergines in a little rapeseed oil, salt and pepper and arrange on a large baking tray. Repeat for the courgettes, if you're using them for a vegan version.
Bake for 30 mins until golden, but not overcooked. Once ready, remove from the oven and set aside.
TIP: You can bake your vegetables in advance and store them in the fridge until you're ready to use them.
Score the chicken breasts in a criss-cross pattern. This will help the flavours to absorb.
Arrange the scored chicken breasts, sliced onions and tomatoes in a large ovenproof dish and sprinkle all the spices over. With your hands, gently “massage” the spices into the mixture so it is evenly distributed and the chicken is well coated.
Cover the dish with foil or a lid, and bake for 20 mins at 180 degrees. Remove from the oven and add the aubergine and passata. Season with salt and pepper. Gently stir to combine and finish with a drizzle of oil.
VEGAN version: Spice the vegetables and add the chickpeas, tossing them gently to ensure they are evenly coated. No need to cook for 20mins at the beginning; add the passata, cover and bank for 30-40mins at 170 degrees.
Cover again and bake at a lower temperature; 170 degrees for 45-60 mins. Ensure the chicken pieces are covered in sauce occasionally during cooking and add a little water if it looks dry.
Once the sauce is thick, remove the dish from the oven. Check the seasoning and adjust if necessary.Ideally, allow the dish to "rest" so the flavours can settle and infuse.