Preheat your oven to 425°F (220°C).
In a large mixing bowl, combine the olive oil, garlic powder, oregano, paprika, salt, and pepper.
Add the chicken breasts to the bowl and coat them evenly with the oil and spice mixture.
On the sheet pan, arrange the halved baby potatoes, broccoli florets, and sliced bell peppers. Drizzle with a little olive oil and season with salt and pepper. Toss to coat the veggies evenly.
Place the marinated chicken breasts on top of the vegetables on the sheet pan.
Bake in the preheated oven for 25-30 minutes, or until the chicken reaches an internal temperature of 165°F (75°C) and the vegetables are tender.
If desired, broil for an additional 2-3 minutes to get a golden color on the chicken.
Remove from the oven and let it rest for a few minutes before serving.
Garnish with chopped fresh parsley, if using, and serve warm.