Preheat oven to 425 degrees.
In a 10-inch round oven-safe pan, over medium heat, add olive oil.
Saute the onion about 1 -2 minutes to sweat the onions.
Add the cubed eggplant and stir frequently until they are soft about 8 minutes.
Stir in the minced garlic, fresh oregano, season to taste with salt and pepper, continue to stir about another 3 minutes.
Remove from the heat and top with the low-fat mozzarella cheese slices.
Top the eggplant/cheese mixture with the zucchini and tomatoes, alternate the veggies to cover the eggplant.
Bake for about 25 minutes.
Remove from oven. Top the vegetables with the Parmesan cheese, basil. If needed, season with salt and pepper.
Place back in the oven until cheese melts, about 2 minutes
Ready to serve. Can also be served at room temperature.