Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper for easy cleanup.
Trim the ends off the Brussels sprouts and halve them, slice the carrots into half-inch rounds, and roughly chop the red onion into bite-sized pieces.
Mince the garlic cloves and finely chop the fresh rosemary and thyme leaves.
Place the chicken breast in the center of the baking sheet and surround it with the prepared vegetables.
Drizzle the extra virgin olive oil over the chicken and vegetables, then sprinkle evenly with the minced garlic, chopped herbs, sea salt, and black pepper.
Toss the vegetables with your hands or tongs to ensure they are well-coated in oil and seasoning, and rub the seasoning into both sides of the chicken.
Roast in the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the vegetables are tender and caramelized.
Allow the chicken to rest for 5 minutes before slicing it against the grain and serving it alongside the roasted vegetables.