Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Peel the carrots and parsnips, then chop them into uniform 1-inch chunks to ensure even roasting.
Mince the garlic cloves and whisk them in a small bowl with the olive oil, dried rosemary, dried thyme, sea salt, and black pepper.
Place the chicken breast and the chopped root vegetables on the prepared baking sheet.
Drizzle the herb oil mixture over everything, using your hands or a brush to coat the chicken and tossing the vegetables until they are well-covered.
Spread the vegetables into a single layer around the chicken to allow for proper airflow and browning.
Roast for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender with golden-brown edges.
Remove from the oven and let the chicken rest for 5 minutes before slicing it into strips and serving alongside the roasted roots.