Put the aubergine slices in a colander set over a bowl, sprinkle with 1 1/2 tsp coarse salt, and toss. Leave them for 30 minutes, until beads of moisture show on the surface. Heat the oven to 220 C / 425 F during the last 15 minutes.

Pat the slices dry with paper towels and don't rinse them. Spread them in a single layer on two parchment-lined 33 x 46 cm / 13 x 18-inch sheet pans, and brush both sides with the 4 tbsp olive oil. Bake for 25 minutes, flipping after 15 minutes, until golden and soft when pressed.

While the aubergine bakes, heat 2 tbsp olive oil in a 30 cm / 12-inch deep skillet over medium heat. Cook the onion for 5 minutes, until soft. Add the beef, break it up with a spoon, and cook for 7 minutes, until browned with no pink left. Spoon off extra fat, leaving about 1 tbsp in the pan.

Stir in the garlic and tomato paste and cook for 1 minute. Pour in the wine and simmer for 2 minutes, scraping up the browned bits. Add the tomatoes, oregano, cinnamon, bay leaf, 1/2 tsp salt, and pepper.

Simmer over medium-low heat for 20 minutes, stirring now and then, until a spoon dragged across the bottom of the pan leaves a clear trail. Remove the bay leaf, stir in the parsley, then taste and add more salt if needed.

Lower the oven to 200 C / 390 F. Spread a thin layer of sauce in a 23 x 33 cm / 9 x 13-inch baking dish. Add half the aubergine slices, overlapping them slightly, then half the remaining sauce. Repeat with the rest of the aubergine and sauce, then sprinkle the graviera on top.

Bake for 20 minutes, until the edges bubble, the top is golden, and the center reads 160 F / 71 C on an instant-read thermometer. Rest for 10 minutes, then cut into 4 squares.