Preheat the oven to 200C/180C Fan/Gas 6.
Cut the aubergines in half from top to bottom and score in a criss-cross pattern through the flesh. Place on a small baking tray and spray with oil. Season with a little black pepper and bake for 30-40 minutes or until very tender and lightly browned.
Meanwhile, spray a large non-stick frying pan with oil and place over a medium heat. Add the onion and cook for five minutes, stirring regularly until softened and lightly browned. Add the cumin, coriander, chilli and cinnamon and cook for a few seconds, stirring constantly.
Pour the tomatoes into the pan. Add the pepper, courgette, chickpeas, coriander and stock. Season with a little salt and lots of ground black pepper and bring to a gentle simmer. Cook for around 20 minutes, stirring occasionally until the vegetables are tender and the sauce is thick.
Just before the sauce is ready, make the couscous. Dissolve the stock cube in 100ml/3½fl oz just-boiled water in a medium bowl. Stir in the couscous, cover and rest for three minutes. Add the lemon zest, coriander and season to taste. Toss well together, using a fork to break up the clumps of couscous.
Divide the aubergines between two plates. Stir the lemon juice into the chickpeas and season to taste. Spoon the spiced chickpeas over the aubergines. Add the couscous and sprinkle with chopped nuts. Garnish with coriander and yoghurt.