Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Peel the carrots and parsnips, then slice them into 1-inch thick rounds or cubes to ensure even cooking.
In a large mixing bowl, combine the chicken breast, sliced carrots, and cubed parsnips.
Mince the garlic and finely chop the fresh rosemary and thyme leaves.
Drizzle the olive oil over the chicken and vegetables, then add the garlic, herbs, sea salt, and black pepper.
Toss everything thoroughly until the chicken and vegetables are well-coated in the oil and herb mixture.
Spread the ingredients in a single layer on the prepared baking sheet, ensuring the chicken is not covered by vegetables.
Roast for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and caramelized.
Remove from the oven and let the chicken rest for 5 minutes before slicing to keep it juicy.
Serve the sliced chicken alongside the roasted root vegetables.