Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper.
Peel and dice the sweet potato into 1-inch cubes, then finely mince the garlic clove and fresh rosemary.
On the prepared sheet pan, toss the sweet potato cubes with 0.25 tablespoons of olive oil and a pinch of sea salt.
Place the potatoes in the oven to roast for 10 minutes, allowing them to begin softening.
While the potatoes roast, rub the chicken breast evenly with 0.25 tablespoons of olive oil, minced garlic, rosemary, salt, and pepper.
Remove the pan from the oven, move the potatoes to one side, and place the chicken breast and broccoli florets on the other side.
Drizzle the remaining 0.25 tablespoons of olive oil over the broccoli and squeeze the fresh lemon juice over both the chicken and the vegetables.
Return the pan to the oven and roast for 18-20 minutes until the chicken reaches an internal temperature of 165°F and the vegetables are golden brown.