Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Peel the carrots and parsnips, then slice them into uniform 1-inch rounds to ensure they roast evenly.
Mince the garlic cloves and finely chop the fresh rosemary and thyme leaves.
In a large mixing bowl, whisk together the olive oil, minced garlic, chopped herbs, sea salt, and black pepper.
Add the chicken breast and the sliced root vegetables to the bowl, tossing thoroughly until everything is well-coated in the herb oil.
Spread the chicken and vegetables in a single layer on the prepared baking sheet, making sure not to crowd the pan.
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 ensure it remains juicy.