Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Peel the carrots and parsnips, then chop them into uniform 1-inch chunks to ensure even roasting.
Mince the garlic cloves and finely chop the fresh rosemary and thyme leaves.
In a large mixing bowl, combine the chicken breast, chopped root vegetables, olive oil, minced garlic, rosemary, thyme, sea salt, and black pepper.
Toss everything thoroughly until the chicken and vegetables are well-coated in the oil and herb mixture.
Spread the mixture in a single layer on the prepared baking sheet, ensuring the chicken pieces are not 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 tender and caramelized.
Remove from the oven and drizzle the fresh lemon juice over the entire tray to brighten the flavors before serving.