Summer Gratin

Ingredients (10)

• 5 tablespoons olive oil,
• 2 medium onions,
• 1 medium garlic clove,
• 1¼ pounds small or medium, ripe tomatoes
• 3/4 pound (2 small) zucchini,
• 3/4 pound (2 small) yellow summer squash,
• 1/4 cup chopped fresh thyme,
• 1 teaspoon salt,
• 1¼ cups grated Parmesan cheese,
• freshly ground black pepper,