Preheat the oven 180°C, fan 160°C, gas 4. Lightly brush a baking sheet with half a tablespoon of oil. Scatter with a few of the oregano leaves and arrange the aubergines over the top. Brush the aubergines with a further half a tablespoon of the oil and bake in the oven for 25 minutes, turning the slices after 15 minutes.
Meanwhile, heat the remaining oil in a non-stick frying pan and cook the onions for 3 minutes until softened. Add the garlic and cumin seeds and fry for a further 2 minutes. Stir in the mince and cook over a medium – high heat for 3 minutes.
Add the chopped and cherry tomatoes and remaining oregano leaves. Season with black pepper and simmer uncovered for 15-17 minutes.
Meanwhile, wilt the spinach leaves, either in the microwave, on full power for 45 seconds, or in a saucepan.
Remove the aubergines from the oven. Lay a few over the base of a 2-litre ovenproof dish, followed by half the mince mixture, half the new potatoes and the wilted spinach. Lay more aubergines over and repeat the layering process, finishing with a layer of aubergines (ideally 4-5 slices). Scatter over the cheese and bake in the oven for 45 minutes.