Preheat the Oven: Preheat your oven to 375°F (190°C).
Prepare Vegetables: Slice the eggplant, zucchini, peppers, onion, and tomatoes into 1/2-inch thick slices. Arrange them into neat rows, either in a baking dish or a circular pattern in a skillet.
Prepare the Sauce: In a small bowl, mix the olive oil, minced garlic, thyme, oregano, salt, and pepper. Drizzle the mixture evenly over the arranged vegetables.
Roast: Cover the baking dish with foil or a lid and bake for 30 minutes. Then, uncover and bake for an additional 15 minutes to allow the vegetables to brown slightly.
Serve: Remove from the oven and let the ratatouille sit for a few minutes. Garnish with fresh basil, if desired. Serve warm as a main or a side dish.