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 uniform 1-inch chunks to ensure even cooking.
Mince the garlic cloves and finely chop the fresh rosemary and thyme leaves.
In a large mixing bowl, combine the chicken breast, chopped root vegetables, olive oil, minced garlic, herbs, sea salt, and black pepper.
Toss the ingredients thoroughly until the chicken and vegetables are evenly coated in the oil and herb mixture.
Spread the mixture onto the prepared baking sheet in a single layer, ensuring the chicken pieces are not crowded by the vegetables.
Roast for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and golden brown.
Remove from the oven and let the chicken rest for 5 minutes before slicing to keep it juicy, then serve immediately alongside the roasted vegetables.