Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Peel and dice the carrots, parsnips, and sweet potato into uniform 1-inch cubes to ensure they roast evenly.
Mince the garlic cloves and finely chop the fresh rosemary and thyme leaves.
In a large mixing bowl, toss the diced root vegetables with 0.5 tbsp of the olive oil, half of the minced garlic, half of the herbs, and half of the salt and pepper.
Rub the chicken breast with the remaining 0.25 tbsp of olive oil, the rest of the garlic, herbs, salt, and pepper.
Spread the seasoned vegetables in a single layer on the prepared baking sheet and place the chicken breast in the center.
Roast for 25-30 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and slightly caramelized.
Remove from the oven and let the chicken rest for 5 minutes before slicing to ensure it remains juicy.