Preheat your oven to 400°F and line a large rimmed sheet pan with parchment paper.
Peel the carrots and parsnips, then slice the carrots into 1/2-inch rounds and cube the parsnips into 1-inch pieces.
Cut the red onion into thick wedges and mince the fresh garlic cloves.
In a large mixing bowl, whisk together the extra virgin olive oil, minced garlic, chopped rosemary, thyme, sea salt, and black pepper.
Add the chicken breast and all the prepared vegetables to the bowl, tossing thoroughly to ensure everything is evenly coated in the herb oil.
Spread the mixture in a single layer on the prepared sheet pan, making sure the chicken and vegetables are not overcrowded.
Roast in the center of the oven for 20-25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender with golden edges.
Remove from the oven and let the chicken rest for 5 minutes before slicing to ensure it stays moist and juicy.