Preheat your oven to 400°F (200°C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Trim the ends of the Brussels sprouts and slice them in half; peel the carrots and cut them into 1-inch thick coins.
Mince the garlic cloves finely and set aside.
In a large mixing bowl, combine the chicken breast, halved Brussels sprouts, and carrot coins.
Drizzle the olive oil over the mixture and add the minced garlic, dried rosemary, dried thyme, sea salt, and black pepper.
Toss everything thoroughly until the chicken and vegetables are evenly coated in the oil and seasonings.
Spread the ingredients in a single layer on the prepared baking sheet, ensuring the chicken pieces are not covered by the vegetables.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and browned at the edges.
Remove from the oven and let the chicken rest for 5 minutes before slicing to keep it juicy.
Plate the sliced chicken alongside the roasted vegetables and serve immediately.