Preheat the oven to 400ºF. Heat a frying pan over a medium high heat, brush the aubergine slices with a little oil and spray a non-stick pan with cooking spray. Fry in batches until golden. Remove from the pan and set aside.
Coat the pan with a little more spray, add the garlic and fry for a minute. Stir in the tomato puree, tomatoes, vinegar and oregano. Simmer gently for a couple of minutes then remove from the heat and season to taste.
Spoon half of the tomato sauce into a shallow roasting dish, arrange the aubergine slices on top then spoon over the remaining sauce. Top with the mozzarella and grated parmesan then bake for 25 minutes until the cheese is bubbling.