Preheat the oven to 425°F (use convection if available; no temperature adjustment required) and line a baking sheet with aluminum foil.
In a large bowl, combine the chicken pieces, onion chunks, whole mushrooms (stem/gill side up), and zucchini pieces.
Drizzle the olive oil over the chicken and vegetables, then sprinkle with paprika, dried oregano, kosher salt, and black pepper.
Toss everything with your hands or tongs until evenly coated with oil and seasonings.
Spread the mixture in a single layer on the prepared baking sheet and roast for about 20 minutes, or until the chicken is cooked through and the vegetables are tender.
Optionally garnish with the minced parsley and serve immediately.