Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Peel the carrots and parsnips, then slice them into half-inch thick rounds; cut the red onion into thick wedges.
In a large mixing bowl, toss the sliced carrots, parsnips, and onions with half of the olive oil, half of the sea salt, and half of the black pepper.
Mince the garlic, rosemary, and thyme, then whisk them together in a small bowl with the remaining olive oil.
Pat the chicken breast dry with a paper towel and rub the herb-garlic oil mixture over both sides of the meat.
Spread the vegetables in a single layer on the prepared baking sheet and place the chicken breast in the center.
Roast for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and slightly caramelized.
Remove from the oven and allow the chicken to rest for 5 minutes before slicing and serving alongside the roasted vegetables.