Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Trim the ends of the Brussels sprouts and slice them in half; peel the carrots and cut them into half-inch thick rounds.
Mince the garlic clove and whisk it in a small bowl with the olive oil, rosemary, thyme, sea salt, and black pepper.
Place the chicken breast, Brussels sprouts, and carrots on the baking sheet and drizzle the herb oil over everything.
Toss the ingredients thoroughly with your hands or tongs to ensure an even coating of oil and spices.
Spread the mixture into a single layer, ensuring the chicken is in the center and the vegetables are not overcrowded.
Roast for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and browned.
Remove from the oven and let the chicken rest for 5 minutes before slicing to ensure it stays moist and flavorful.