Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper for easy cleanup.
Pat the chicken breast dry with a paper towel and cut into even 1-inch bite-sized pieces.
Peel and chop the carrots and parsnips into 1/2-inch rounds; slice the red onion into small wedges.
In a large mixing bowl, combine the chicken pieces, carrots, parsnips, and red onion.
Mince the garlic cloves and finely chop the fresh rosemary and thyme.
Drizzle the olive oil over the chicken and vegetable mixture, then add the minced garlic, herbs, sea salt, and black pepper.
Toss everything together until the chicken and vegetables are thoroughly and evenly coated with the seasoned oil.
Spread the mixture in a single layer on the prepared baking sheet, ensuring the pieces are spread out to allow for proper roasting.
Roast for 20-25 minutes, tossing the ingredients halfway through, until the chicken is cooked through and the vegetables are golden and tender.