Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Peel and slice the carrots and parsnips into 1-inch rounds, and cut the red onion into thick wedges.
In a large mixing bowl, toss the sliced vegetables with 0.5 tablespoon of olive oil, half of the minced garlic, and a pinch of sea salt and black pepper.
Spread the vegetables in a single layer on the prepared baking sheet and roast for 10 minutes.
While the vegetables are roasting, prepare the chicken by rubbing it with the remaining 0.5 tablespoon of olive oil, remaining garlic, rosemary, thyme, salt, and pepper.
Remove the baking sheet from the oven, move the vegetables to the outer edges, and place the chicken breast in the center.
Return the pan to the oven and roast for an additional 20-25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and caramelized.
Let the chicken rest for 5 minutes before slicing it against the grain and serving alongside the roasted root vegetables.