Preheat your oven to 400°F (200°C) 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 wedges.
Mince the garlic cloves and finely chop the fresh rosemary and thyme leaves.
In a large bowl, toss the chopped root vegetables and red onion with half of the olive oil, salt, and pepper.
Pat the chicken breast dry with a paper towel and rub with the remaining olive oil, minced garlic, rosemary, thyme, salt, and pepper.
Arrange the vegetables in a single layer on the prepared baking sheet, leaving space in the center for the chicken.
Place the chicken breast in the center and roast for 25-30 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender.
Let the chicken rest for 5 minutes before slicing and serving with the roasted vegetables.