Preheat your oven to 400°F and line a large rimmed baking sheet with parchment paper.
Wash the sweet potato and dice it into 1/2-inch cubes, and chop the broccoli into uniform bite-sized florets.
Mince the garlic cloves and finely chop the fresh rosemary leaves.
In a large mixing bowl, toss the sweet potato cubes and broccoli florets with half of the olive oil, sea salt, and black pepper until evenly coated.
Pat the chicken breast dry with a paper towel, then rub it with the remaining olive oil, minced garlic, chopped rosemary, and dried oregano.
Spread the vegetables onto the prepared baking sheet in a single layer, leaving space in the center for the chicken.
Place the chicken breast in the center and roast for 22-25 minutes, or until the chicken reaches an internal temperature of 165°F.
Remove from the oven and let the chicken rest for 5 minutes to lock in the juices before slicing and serving with the roasted vegetables.