Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper.
Trim the ends off the Brussels sprouts and cut them in half; peel the carrots and slice them into 1/2-inch thick rounds.
Mince the garlic cloves and finely chop the fresh rosemary and thyme leaves.
In a large mixing bowl, combine the chicken breast, Brussels sprouts, and carrots.
Drizzle the olive oil over the chicken and vegetables, then add the minced garlic, chopped herbs, sea salt, and black pepper.
Toss everything thoroughly until the chicken and vegetables are evenly coated in the oil and seasonings.
Spread the mixture in a single layer on the prepared baking sheet, ensuring space between the pieces for even roasting.
Roast for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and lightly charred.
Remove from the oven and let the chicken rest for 5 minutes before slicing to ensure it stays juicy.