1. Preheat oven grill to high. Brush eggplant slices with 1 tablespoon of oil and cook for 3 minutes, until golden. Turn, brush again with 1 tablespoon of oil and cook for another 3 minutes. Set aside.

2. Preheat oven to 180ºC. Heat remaining oil in a large frying pan on medium. Sauté onion and garlic for 5 minutes, until softened. Increase heat to high and add mince. Cook for 5 minutes, breaking up any lumps with a spoon, until brown and liquid has evaporated. Add tomato and oregano and season to taste. Simmer for 15 minutes, stirring occasionally, until sauce thickens.

3. Meanwhile, make Cheese Sauce. Melt butter in a saucepan on low. Add flour and stir for 1 minute. Whisk in milk. Increase heat to medium and cook for 3 minutes, stirring, until sauce thickens. Remove from heat and whisk in egg yolks, parmesan and nutmeg. Season to taste.

4. Lay one-third of eggplant in base of an 8-cup ovenproof dish. Top with half of mince mixture. Repeat layers once more and top with remaining eggplant. Spoon over Cheese Sauce and bake for 45 minutes, until golden.
Serve hot or at room temperature.