Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Peel and chop the carrots and parsnips into 1-inch chunks, and slice the red onion into thick wedges.
Mince the garlic cloves and finely chop the fresh rosemary and thyme leaves.
In a large mixing bowl, toss the prepared vegetables with half of the olive oil, half of the salt, and half of the pepper.
Pat the chicken breast dry with a paper towel and rub with the remaining olive oil, minced garlic, chopped herbs, and the rest of the salt and pepper.
Spread the vegetables in a single layer on the baking sheet and place the seasoned chicken breast in the center.
Roast for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165°F and the root vegetables are tender and golden.
Remove from the oven and let the chicken rest for 5 minutes before slicing it against the grain and serving alongside the roasted vegetables.