Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Peel and dice the sweet potato, carrots, and parsnips into uniform 1-inch cubes to ensure even cooking.
In a small bowl, whisk together the olive oil, minced garlic, dried rosemary, dried thyme, sea salt, and black pepper.
Place the chicken breast and chopped vegetables in a large mixing bowl and drizzle with the herb oil, tossing until every piece is well coated.
Spread the mixture onto the prepared baking sheet in a single layer, ensuring the chicken has space around it to roast properly.
Bake for 25 to 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.