Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with unbleached parchment paper.
Peel the carrots and parsnips, then slice them into half-inch thick rounds; peel the red onion and cut it into small wedges.
In a small glass bowl, whisk together the extra virgin olive oil, minced garlic, rosemary, thyme, sea salt, and black pepper until well combined.
Place the chicken breast and all the chopped root vegetables onto the baking sheet, ensuring they are spread out for even roasting.
Drizzle the herb oil over the chicken and vegetables, using your hands or a spatula to toss everything until thoroughly and evenly coated.
Arrange the chicken in the center of the pan and surround it with the vegetables in a single layer to ensure they caramelize rather than steam.
Roast for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and golden.
Remove from the oven and let the chicken rest for 5 minutes before slicing it against the grain to maintain juiciness.