Preheat the oven to 350°. Coat a 9-inch baking dish with olive oil. Spread the potatoes in the dish in an even layer; drizzle with oil and season with salt and pepper. In a bowl, combine the bell pepper, onion, garlic and thyme and season with salt and pepper. Arrange two-thirds of the bell pepper mixture over the potatoes and drizzle with oil. Top with the tomatoes and the zucchini; drizzle with oil and season with salt and pepper. Cover with the remaining bell pepper mixture and sprinkle with the cheese.