Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Peel the sweet potato, carrots, and parsnips, then dice them into uniform 1-inch cubes to ensure even roasting.
Mince the garlic cloves and finely chop the fresh rosemary and thyme leaves.
In a large mixing bowl, toss the diced root vegetables with half of the olive oil, half of the minced garlic, and half of the fresh herbs.
Pat the chicken breast dry with a paper towel and rub it thoroughly with the remaining olive oil, garlic, herbs, sea salt, and black pepper.
Spread the seasoned vegetables across the prepared baking sheet in a single layer, making space to place the chicken breast in the center.
Roast in the oven for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are fork-tender and golden.
Remove from the oven and let the chicken rest for 5 minutes before slicing to keep the juices intact, then serve alongside the roasted roots.