Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Peel the carrots and parsnips, then chop them into uniform 1-inch chunks to ensure even cooking.
In a mixing bowl, toss the chopped root vegetables with half of the olive oil, one minced garlic clove, and a pinch of salt and pepper.
Place the chicken breast on the prepared baking sheet and rub with the remaining olive oil, the second minced garlic clove, rosemary, thyme, salt, and pepper.
Scatter the seasoned vegetables around the chicken in a single layer, ensuring they aren't overcrowded.
Roast in the center of the oven for 25 to 30 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are fork-tender.
Remove from the oven and let the chicken rest for 5 minutes before slicing to keep the meat juicy.
Serve the sliced chicken alongside the roasted vegetables, drizzling any pan juices over the top for extra flavor.