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 everything thoroughly until the chicken and vegetables are well-coated in the oil and herb mixture.
Spread the mixture onto the prepared baking sheet in a single layer, ensuring the pieces aren't overcrowded.
Roast in the oven for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and lightly caramelized.
Remove from the oven and let the chicken rest for 5 minutes before slicing to keep it juicy.