Place the bread, garlic and parsley in a food processer and turn until you have fine green breadcrumbs. Add 1 tbsp of the olive oil and turn again briefly. Transfer to a bowl. Meanwhile brush a deep, ovenproof baking dish with a little of the remaining oil.
Sprinkle a third of the breadcrumbs over the base of the dish, cover with layers of aubergine, then courgette, potato and tomato, seasoning each layer. Repeat the layers, finishing with a layer of tomatoes. Heat the oven to 190C – Gas 5. Cover the baking dish with foil and bake for 35 minutes.
Remove the foil, scatter the remaining breadcrumbs over the top, and drizzle with the remaining oil. Return to the oven for a further 20 minutes or until the vegetables are cooked and the top is nicely browned.