Preheat the oven to 200°C (392°F).
Wash the eggplant and slice it into finger-thick rounds. Place the slices on a baking tray lined with parchment paper. Drizzle both sides with lemon juice and olive oil, then sprinkle with salt.
Put the tomato purée into a bowl and season it with salt, oregano, and basil. Mix well and spoon it onto the eggplant slices.
Dice the ham and sprinkle it over the sauce.
Dice the feta cheese and scatter it on top as well.
Place the tray in the oven and bake for about 15 minutes, until the tops become crispy. Remove from the oven, transfer to a large plate, and while still hot, sprinkle with grated cheese so it melts nicely on top.
Serve with fresh arugula!