Preheat oven to 425°F. Line two baking sheets with parchment paper or aluminum foil for easy cleanup.
Pat chicken breasts dry with paper towels on cutting board. In a small mixing bowl, combine 1 tablespoon olive oil, Italian seasoning, garlic powder, paprika, salt, and pepper.
Rub seasoning mixture all over chicken pieces. Set aside.
In a large mixing bowl, combine halved potatoes, broccoli florets, bell peppers, onion wedges, and cherry tomatoes. Drizzle with remaining 2 tablespoons olive oil and sprinkle with Italian seasoning, salt, and pepper. Toss with tongs to coat evenly.
Arrange vegetables on the two baking sheets in a single layer, spreading them out for even roasting. Place potatoes on one side since they take longest to cook.
Nestle seasoned chicken pieces among the vegetables on the baking sheets, spacing everything evenly.
Roast for 25-30 minutes, rotating pans halfway through, until chicken reaches 165°F internal temperature on meat thermometer and vegetables are tender with golden edges.
Remove from oven and let cool on cutting board for 10 minutes before portioning.
Divide chicken and vegetables evenly among 5 meal prep containers. Seal and refrigerate for up to 5 days.
To serve: Microwave for 2-3 minutes until heated through. Garnish with fresh parsley, squeeze of lemon, and parmesan if desired.