Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Prepare the vegetables by peeling and slicing the carrots and parsnips into 1/2-inch thick rounds, and cutting the red onion into thin wedges.
In a large mixing bowl, toss the sliced carrots, parsnips, and onions with 0.5 tablespoon of olive oil, half of the minced garlic, and half of the fresh rosemary and thyme.
Pat the chicken breast dry with a paper towel and rub it with the remaining 0.25 tablespoon of olive oil, garlic, herbs, sea salt, and black pepper.
Spread the seasoned vegetables in a single layer on the prepared baking sheet, leaving space in the center to place the chicken breast.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and lightly browned.
Remove from the oven and let the chicken rest for 5 minutes to lock in the juices before slicing it against the grain.
Serve the sliced chicken alongside the roasted root vegetables, drizzling any remaining pan juices over the top.