1. Preheat the oven to 200˚C, gas mark 6. Cut the tops off the aubergines, then slice them lengthways into 0.5cm strips. Lay the slices, in batches if needed, side by side on 2 large, greased baking sheets. Drizzle with olive oil and season, then roast for 20 minutes until soft and lightly golden.
2. Meanwhile, place the croutons in a blender and pulse several times until you have coarse crumbs. Spread one-third of the tomato sauce over the base of a medium roasting tin, then cover this with half the roasted aubergine. Add another third of the tomato sauce and half the grated cheese. Make another layer with the rest of the aubergines and remaining tomato sauce.
3. Sprinkle over the rest of the grated cheese and bake for 15 minutes, then scatter over the crumbs and bake for another 10 minutes, until bubbling and piping hot. Serve with a green salad, if liked.