Preheat the oven on to 180°C.
Put the tomatoes into a large baking tray.
Cut the onion into thin wedges. Bash the garlic in its skin. Scatter these around the tomatoes.
Drizzle with the oil and dust with the spices. Season with salt and pepper. Combine well, then bake for 15 minutes.
Add most of the chickpeas and bake for a further 15-20 minutes until the tomatoes and onion start browning.
Transfer the baked vegetables and juices into a pan. Discard any burnt onion & tomato skin together with the garlic skin. Add the garlic flesh to the pan.
Add the hot stock and fresh herbs, then (using a stick blender) process until you get a smooth, velvety soup.
Add the remaining chickpeas and heat the soup up just before serving.
Serve warm.