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 slice them into uniform 1/2-inch thick rounds to ensure even cooking.
Place the chicken breast in the center of the baking sheet and surround it with the carrots and parsnips.
Mince the garlic cloves finely and sprinkle them over the chicken and vegetables.
Drizzle the olive oil over everything, then season evenly with dried rosemary, dried thyme, sea salt, and black pepper.
Use your hands or tongs to toss the vegetables and coat the chicken thoroughly in the oil and herb mixture.
Spread the ingredients into a single layer, ensuring the chicken is not covered by the vegetables.
Roast for 22-25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and lightly browned.
Remove from the oven and drizzle with fresh lemon juice to brighten the flavors before serving.