Heat 1 cm (½ inch) oil in a large frying pan over a high heat until the surface of the oil seems to shimmer slightly. Add the aubergines, in batches, and fry until golden on both sides. Remove with a slotted spoon and drain on a dish lined with kitchen paper. Scatter with the oregano and season lightly with salt.
Cook the pasta in a large saucepan of salted boiling water according to the packet instructions until almost al dente. Drain, then stir in a bowl with the tomato sauce, mozzarella and Parmesan. Season with salt and pepper.
Meanwhile, line the base and sides of an 18 cm (7 inch) springform cake tin with the aubergine slices. Overlap the slices slightly, to ensure that there are no gaps, then fill the tin with the pasta mixture. Press down so that the pasta is tightly packed, then cover with the remaining aubergine slices.
Scatter the breadcrumbs over the top of the pasta cake and bake on a baking sheet in a preheated oven, 200°C (400°F), Gas Mark 6, for 15 minutes until golden brown. Leave the cake to stand for 15 minutes before unclipping and removing the ring to serve. Don't attempt to remove the cake from its base, as it will most probably break in the process.