Preheat your oven to 400°F (200°C) and line a large baking sheet with parchment paper.
Mince the garlic cloves and finely chop the fresh rosemary and thyme leaves.
In a small mixing bowl, combine 0.5 tablespoons of olive oil with the minced garlic, rosemary, thyme, sea salt, and black pepper to create a herb paste.
Pat the chicken breast dry with a paper towel and rub the herb paste evenly over all sides of the meat.
Peel and cube the sweet potato into 1/2-inch pieces, then place them on the baking sheet along with the broccoli florets.
Drizzle the remaining 0.5 tablespoons of olive oil over the vegetables and toss to coat, spreading them out into a single layer.
Nestle the herb-rubbed chicken breast onto the baking sheet among the vegetables.
Roast in the center of the oven for 20-25 minutes, or until the chicken reaches an internal temperature of 165°F and the sweet potatoes are fork-tender.
Remove from the oven and drizzle the fresh lemon juice over the chicken and roasted vegetables before serving.