Preheat oven to 400℉. Line a large rimmed baking sheet with parchment paper.
Transfer the zucchini and red onion to your baking sheet. Add the olive oil, salt, pepper, garlic powder, onion powder, Italian herb blend and toss until well coated. Spread vegetables out evenly (it doesn't matter if they overlap). Roast for 22-25 minutes. Remove the pan from the oven and lower oven temperature to 375℉.
In a large bowl, mix together your eggs, feta, parmesan, breadcrumb, tomatoes, olives, parsley, salt and pepper to taste (keep in mind the feta and olives are salty). Fold in the roasted zucchini and onions. Spray the pie dish with olive oil. Transfer half of the batter to the pie dish. Sprinkle evenly with mozzarella and then top with the rest of the zucchini mixture. Top with another sprinkle of grated parmesan. Bake for 50 minutes or until golden brown and set on top. Allow to cool 10 minutes prior to slicing.