Sprinkle the eggplant slices with salt and let them sit for 10 minutes to draw out moisture. Pat them dry.
In a baking dish, layer the eggplant slices, tomato sauce, mozzarella cheese, and parmesan cheese. Repeat the layers until all ingredients are used, finishing with a layer of cheese on top.
Drizzle olive oil over the top and season with black pepper.
Bake in the preheated oven for 40 minutes, or until the top is golden and bubbly.
Let it cool for a few minutes before serving.
Notes:
This casserole can be made ahead and refrigerated. Just bake it when you're ready to eat.