Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Prepare the vegetables by peeling and chopping the carrots and parsnips into 1-inch chunks, halving the Brussels sprouts, and finely mincing the garlic.
Pat the chicken breast dry with a paper towel and season both sides evenly with half of the sea salt, black pepper, rosemary, and thyme.
In a large mixing bowl, toss the prepared carrots, parsnips, and Brussels sprouts with the olive oil, minced garlic, and the remaining herbs and seasonings.
Spread the vegetable mixture in a single layer on the baking sheet, leaving an open space in the center.
Place the seasoned chicken breast in the center of the sheet and roast for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F.
Remove from the oven and let the chicken rest for 5 minutes to lock in the juices before slicing and serving with the roasted vegetables.