Sauté onion in 2 tbsp olive oil for 10 minutes until soft.
Brown the lamb mince in batches and combine with onions and garlic.
Add cinnamon, allspice, tomatoes, herbs, and wine, then simmer for 1 hour.
Salt the sliced aubergines in a colander for 30 minutes to remove bitterness.
Melt butter, stir in flour and milk to create a thickened béchamel sauce.
Stir 55g each of parmesan and gruyère into the sauce and season.
Rinse aubergines, dust with flour, and fry in batches until golden.
Whisk the egg and egg yolks into the cooled cheese sauce.
Layer mince and aubergines in a dish, topping with sauce and remaining cheese.
Bake at 180°C for 50-60 minutes until golden.