Preheat your oven to 400°F (200°C) and line a large rimmed sheet pan with parchment paper for easy cleanup.
Cut the chicken breast into uniform 1-inch bite-sized pieces to ensure even cooking.
Chop the broccoli into small florets, dice the red bell pepper into 1-inch squares, and thinly slice the red onion.
Place the chicken and all the vegetables onto the prepared sheet pan.
Drizzle the extra virgin olive oil over the chicken and vegetables, then sprinkle evenly with garlic powder, dried oregano, sea salt, and black pepper.
Use your hands or tongs to toss everything together until every piece is well-coated with the oil and seasonings.
Spread the mixture out into a single layer, ensuring there is space between the pieces so they roast rather than steam.
Roast in the oven for 20 to 25 minutes, or until the chicken is cooked through and the vegetables have developed golden-brown caramelized edges.
Remove from the oven and garnish with freshly chopped parsley.
For meal prep, allow the mixture to cool slightly before dividing into airtight containers.