Cut the eggplant into round slices about 1 cm thick (3/8 inch), then with a sharp knife score a grid on top (don't cut all the way through).
Place the slices on a baking tray lined with parchment paper, then drizzle with olive oil and sprinkle some salt on each slice.
Bake in the oven for about 15 minutes.
Meanwhile, prepare the tomato sauce. In a bowl, add the plain tomato sauce, then add the ½ tsp of salt, ½ tbsp of good olive oil and 1/8 tsp of dried Oregano. Mix well and set aside. Adjust seasonings to taste.
Remove the tray from the oven, then add 1 tbsp of tomato sauce on each slice and a piece of Mozzarella cheese.
Return the eggplant to the oven and bake another 10-15 minutes.
The eggplants and the mozzarella will make a lot of water, don’t worry, it’s normal. Just lift the slices with a spatula and place them on a plate before serving.