Preheat your oven to 400°F (200°C) and line a large sheet pan with parchment paper for easy cleanup.
Mince the garlic and whisk it in a small bowl with the olive oil, lemon juice, dried rosemary, sea salt, and black pepper.
Slice the baby potatoes in half and chop the carrots into bite-sized rounds.
Place the chicken breast, halved potatoes, carrots, and broccoli florets on the prepared sheet pan.
Drizzle the lemon-herb oil mixture over the chicken and vegetables, tossing well to ensure every piece is evenly coated.
Arrange the chicken in the center and spread the vegetables in a single layer around it.
Roast for 20-25 minutes, or until the chicken reaches an internal temperature of 165°F and the potatoes are fork-tender.
Let the chicken rest for 5 minutes before slicing to keep it juicy, then serve immediately.