Preheat your oven to 400°F (200°C). Grease a 9x13-inch baking dish with cooking spray or a little olive oil.
In a large bowl, combine the sliced zucchinis, chicken pieces, cherry tomatoes, and red onion. Drizzle with olive oil and sprinkle with oregano, garlic powder, salt, and black pepper. Toss everything together until well coated.
Transfer the mixture to the prepared baking dish, spreading it out evenly.
Bake in the preheated oven for 25-30 minutes, or until the chicken is cooked through and the vegetables are tender.
Remove the dish from the oven and sprinkle the crumbled feta cheese on top. Return to the oven for an additional 5 minutes, until the feta is slightly melted.
Garnish with fresh parsley before serving.