Preheat your oven to 400°F (200°C).
Line a sheet pan with parchment paper for easy cleanup.
In a large bowl, toss the mixed vegetables with olive oil, garlic powder, oregano, salt, and pepper.
Arrange the seasoned vegetables evenly on the sheet pan.
Season the chicken breasts with salt, pepper, and a drizzle of olive oil.
Place the chicken breasts on top of the vegetables.
Roast in the preheated oven for 25-30 minutes until chicken is cooked through.
Use a meat thermometer to ensure chicken reaches 165°F (75°C).
Let the dish rest for 5 minutes before serving.
Garnish with fresh herbs if desired.