Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Peel and chop the carrots and parsnips into 1-inch rounds or chunks, and slice the red onion into thin wedges.
In a large mixing bowl, combine the chicken breast, carrots, parsnips, and onion wedges.
Drizzle the olive oil over the chicken and vegetables, then add the minced garlic, rosemary, thyme, sea salt, and black pepper.
Toss everything thoroughly until the chicken and vegetables are evenly coated in the oil and herbs.
Spread the mixture in a single layer on the prepared baking sheet, ensuring the chicken pieces are not overcrowded.
Roast for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165°F and the root vegetables are tender and slightly caramelized.
Remove from the oven and let the chicken rest for 5 minutes before slicing to keep it juicy.