Put the potatoes in a pan of water. Bring to the boil, then cook for 15 minutes. Drain, let the potatoes cool, then cut them into 5mm thick slices.
Preheat the oven to 180°C.
Cut the onion into thin rounds. Finley chop the garlic. Cut the tomatoes in half, the red pepper into slices.
Lightly grease a baking dish with oil and create a layer of potatoes, then arrange the onion, red pepper, tomatoes, sweetcorn and chickpeas on top.
Drizzle with half of the oil and scatter the garlic over the dish, then dust with the spices and salt & pepper. Pour over half of the passata.
Add the rest of the potatoes, drizzle with the remaining oil & cover with passata, then season with salt & pepper.
For a vegetarian version you can cover the top with sour cream, grated cheese, ricotta (or cream cheese). .
Bake in the oven for 25-30 minutes until golden, then serve.