Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Chop the carrots, parsnips, and red onion into uniform 1-inch pieces to ensure even cooking.
In a large mixing bowl, toss the chopped vegetables with half of the olive oil, minced garlic, rosemary, thyme, salt, and pepper.
Place the chicken breast on the prepared baking sheet and rub with the remaining olive oil and a pinch of the herb mixture.
Arrange the seasoned root vegetables in a single layer around the chicken breast on the tray.
Roast in the center of the oven for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender.
Remove from the oven and let the chicken rest for 5 minutes before slicing to keep it juicy.
Serve the sliced chicken alongside the roasted root vegetables and enjoy immediately.