Preheat oven to 400 degrees F. Line a baking sheet with aluminum foil and spray with cooking spray.
Place sliced zucchini and onion in a single layer on prepared baking sheet. Drizzle or spray lightly with olive oil; season with salt and pepper, to taste.
Roast zucchini and onion in oven for approximately 15-20 minutes, or until reach desired tenderness. Set aside to cool to room temperature.
Spread hummus on one slice of bread.
Top hummus with spinach leaves, red peppers, roasted zucchini and onion, olives, banana peppers, and feta cheese. Top with additional slice of bread.