Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Peel and chop the carrots, parsnips, and sweet potato into uniform 1-inch chunks to ensure even roasting.
In a large bowl, whisk together the olive oil, minced garlic, chopped rosemary, thyme, sea salt, and black pepper.
Add the chicken breast and chopped root vegetables to the bowl, tossing thoroughly until everything is well-coated in the herb oil.
Spread the mixture in a single layer on the prepared sheet pan, ensuring the chicken has enough space around it to brown properly.
Roast for 25-30 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and golden-brown.
Let the chicken rest for 5 minutes before slicing to keep it juicy, then serve alongside the roasted vegetables.