Preheat the oven to 375°F (190°C)
Slice eggplant, zucchini, yellow squash, tomatoes, and bell peppers into thin rounds or half-moons
Dice onion and mince garlic
Heat olive oil in a skillet over medium heat
Sauté onion until softened
Add garlic and cook briefly
Stir in crushed tomatoes, thyme, basil, salt, and pepper
Simmer the sauce for a few minutes
Spread the tomato sauce in the bottom of a baking dish
Arrange the sliced vegetables in overlapping rows or a spiral pattern over the sauce
Drizzle with olive oil
Season with salt, pepper, and herbs
Cover with foil and bake for 30 minutes
Remove foil and bake for 15 to 20 minutes more until vegetables are tender
Let cool slightly before serving
Garnish with fresh basil if desired