2 pounds fresh zucchini (about 3–4 medium zucchini)
1/2 small red onion
6 medium fresh plum tomatoes
3 tablespoons extra virgin olive oil
1 teaspoon kosher salt
1 teaspoon herbes de Provence (or chopped thyme, marjoram, or savory)
1 teaspoon freshly ground black pepper
1 cup grated Gruyère cheese
Olive oil for drizzling
Rinse the zucchini and remove ends. Thinly slice into 1/8-inch rounds. Cut onion in half and thinly slice. Slice tomatoes lengthwise into 1/4-inch slices. Place the zucchini, onion, olive oil, salt, herbes de Provence, pepper, and cheese in a large mixing bowl; mix well.
Oil the inside of a ceramic baking dish and add zucchini mixture. Lay the tomato slices overlapping to cover the zucchini. Drizzle with olive oil and set in the oven. Bake for about 40 minutes, or until vegetables are tender, top is bubbling lightly, and tomatoes are lightly charred. Remove and let rest for 10 minutes before serving.