Preheat your oven to 400°F and line a large baking sheet with parchment paper.
Pat the chicken breast completely dry with a paper towel to ensure the surface gets crispy during roasting.
In a small mixing bowl, whisk together the olive oil, lemon juice, lemon zest, rosemary, garlic powder, sea salt, and black pepper.
Toss the cubed sweet potatoes in half of the lemon-herb oil mixture until evenly coated and spread them onto the baking sheet.
Brush the remaining herb oil mixture over both sides of the chicken breast and place it on the baking sheet next to the potatoes.
Roast in the center of the oven for 20 to 25 minutes, or until the chicken reaches an internal temperature of 165°F and the potatoes are tender.
While the chicken is roasting, steam the broccoli florets in a steamer basket for about 5 minutes until they are bright green and tender-crisp.
Remove the chicken from the oven and let it rest for 5 minutes before slicing and serving with the roasted potatoes and steamed broccoli.