Preheat oven to 375°F (190°C). Lightly grease a baking dish or casserole pan.

Heat 1 tablespoon olive oil in a skillet over medium heat. Sauté onion and bell peppers for 5 minutes until softened.

Add garlic and cook for 30 seconds until fragrant. Stir in crushed tomatoes, thyme, oregano, basil, salt, and black pepper. Simmer for 5 minutes.

Spread the tomato sauce mixture evenly in the bottom of the baking dish.

Arrange sliced eggplant, zucchini, and tomatoes in alternating overlapping rows or spiral patterns over the sauce.

Drizzle remaining olive oil over vegetables. Cover tightly with foil.

Bake for 35 minutes covered, then uncover and bake an additional 15 minutes until vegetables are tender and slightly caramelized.

Let rest for 5 minutes before serving. Garnish with fresh parsley or basil.