Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Peel and slice the carrots and parsnips into uniform 1/2-inch thick rounds to ensure even cooking.
In a small bowl, whisk together the olive oil, rosemary, thyme, sea salt, and black pepper.
Place the chicken breast, sliced root vegetables, and whole garlic cloves on the prepared baking sheet.
Drizzle the herb oil mixture over the chicken and vegetables, tossing the vegetables and rubbing the chicken to coat thoroughly.
Arrange everything in a single layer, ensuring the chicken is in the center of the pan.
Roast for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are golden and tender.
Let the chicken rest for 5 minutes before slicing to keep it juicy, then serve alongside the roasted vegetables.