Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Peel and chop the carrots and parsnip into 1-inch chunks, and halve the Brussels sprouts.
Mince the garlic cloves finely.
In a large mixing bowl, combine the chopped vegetables and the whole chicken breast.
Drizzle with avocado oil and sprinkle with minced garlic, rosemary, thyme, sea salt, and black pepper.
Toss everything thoroughly until the chicken and vegetables are evenly coated in oil and spices.
Spread the mixture onto the prepared baking sheet in a single layer, ensuring the chicken is in the center.
Roast 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 let the chicken rest for 5 minutes before slicing into strips.
Serve the sliced chicken alongside the roasted root vegetables.