How to Make It
Preheat oven to 450°.
Heat a skillet over medium-high heat. Add 1 tablespoon oil; swirl to coat. Add onion, bell pepper, and garlic to pan; sauté 4 minutes. Add wine, salt, and black pepper; cook 1 minute. Spread onion mixture in bottom of a shallow 2-quart broiler-proof baking dish. Arrange zucchini and squash slices in a single layer over onion mixture.
Place bread in a mini food processor; pulse until coarsely ground. Combine remaining 1 tablespoon oil, breadcrumbs, oregano, and cheese in a bowl; sprinkle over squash mixture. Bake at 450° for 8 minutes. Preheat broiler to high (do not remove dish from oven). Broil 2 minutes or until browned. Drizzle with vinegar.