Peel and finely chop the onions and garlic cloves. Peel and cut the aubergine into 1.5–2cm cubes. Set a wide, shallow flameproof casserole that has a lid over a medium heat and add enough olive oil to cover the base. Fry the aubergine for around 5 minutes until golden. Season as you go and stir just a couple of times; you want to get a nice crust. When it’s golden, add the minced meat and increase the heat to high. Break the meat up with a wooden spoon and season it well. Add the ground cinnamon, dried oregano and cayenne. Brown for a few minutes, then add the chopped onion and garlic and fry for a further 10 minutes.

Meanwhile, preheat the oven to 190°C/170 fan/gas mark 5. Stir the tomato purée into the meat, fry for a few minutes, then pour in the stock. Bring to the boil, then reduce the heat to a simmer while you slice the potatoes. Scrub, then slice them as finely as you can, 2–3mm thick. Remove the casserole from the hob and lay the potatoes over the top, overlapping them as you go, a bit like a hotpot. Season and sprinkle with a little extra oregano, drizzle with olive oil and cover the casserole with the lid. Place the covered dish in the oven for 30 minutes, removing the lid for the last 10 minutes, until the potatoes are tender.

Mix the mascarpone, Greek yoghurt, egg and egg yolk in a bowl. Finely grate in most of the Parmesan, season and stir it in. Remove the casserole from the oven, pour over the sauce, then finely grate over the remaining Parmesan. Return to the oven, without the lid, and bake for a further 25–30 minutes, until golden all over and bubbling. Leave to rest for 5 minutes before serving.