Preheat your oven to 400°F and line a large sheet pan with parchment paper.
Peel and chop the carrots and parsnips into 1-inch chunks, and slice the red onion into thick wedges.
Mince the garlic cloves and finely chop the fresh rosemary and thyme leaves.
In a large bowl, toss the chopped carrots, parsnips, and onion with half of the olive oil, half of the minced garlic, and a pinch of salt and pepper.
Place the chicken breast on the prepared sheet pan and rub with the remaining olive oil, garlic, rosemary, thyme, salt, and pepper.
Arrange the seasoned root vegetables in a single layer around the chicken on the pan.
Roast for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are fork-tender and golden.
Allow the chicken to rest for 5 minutes before slicing to keep the meat juicy and flavorful.