Preheat your oven to 400°F (200 °C) and line a large rimmed baking sheet with parchment paper for easy cleanup.
Pat the chicken breast completely dry with paper towels and place it on one side of the prepared baking sheet.
In a small mixing bowl, whisk together half of the olive oil, the lemon juice, lemon zest, minced garlic, oregano, garlic powder, salt, and pepper.
Brush the herb and lemon mixture generously over both sides of the chicken breast to ensure deep flavor.
Place the broccoli florets on the other side of the baking sheet, drizzle with the remaining olive oil, and toss with a small pinch of additional salt and pepper.
Roast in the center of the oven for 20-25 minutes, or until the chicken reaches an internal temperature of 165°F and the broccoli is tender with charred edges.
Remove from the oven and let the chicken rest for 5 minutes before slicing to keep it juicy, then serve immediately alongside the roasted broccoli.