Preheat the oven to 375°F (190°C).
Sauté onion and garlic in olive oil over medium heat until softened.
Add diced eggplant to the pan and sauté for about 5-7 minutes until soft.
Add zucchini and continue to cook for 3-4 minutes until tender.
Stir in diced tomatoes, oregano, and salt; simmer for 10 minutes.
In a large bowl, combine cooked pasta with vegetable mixture.
Transfer the mixture into a baking dish; top with mozzarella and Parmesan.
Bake in preheated oven for 25-30 minutes or until the cheese is golden.
Allow to cool for 5-10 minutes before serving.